全文获取类型
收费全文 | 1487篇 |
免费 | 29篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 13篇 |
化学工业 | 223篇 |
金属工艺 | 4篇 |
机械仪表 | 33篇 |
建筑科学 | 57篇 |
矿业工程 | 4篇 |
能源动力 | 23篇 |
轻工业 | 120篇 |
水利工程 | 22篇 |
石油天然气 | 3篇 |
无线电 | 154篇 |
一般工业技术 | 258篇 |
冶金工业 | 423篇 |
原子能技术 | 9篇 |
自动化技术 | 172篇 |
出版年
2023年 | 12篇 |
2022年 | 12篇 |
2021年 | 21篇 |
2020年 | 16篇 |
2019年 | 29篇 |
2018年 | 19篇 |
2017年 | 29篇 |
2016年 | 25篇 |
2015年 | 15篇 |
2014年 | 21篇 |
2013年 | 75篇 |
2012年 | 43篇 |
2011年 | 58篇 |
2010年 | 45篇 |
2009年 | 32篇 |
2008年 | 58篇 |
2007年 | 56篇 |
2006年 | 43篇 |
2005年 | 36篇 |
2004年 | 44篇 |
2003年 | 44篇 |
2002年 | 25篇 |
2001年 | 38篇 |
2000年 | 41篇 |
1999年 | 44篇 |
1998年 | 96篇 |
1997年 | 72篇 |
1996年 | 45篇 |
1995年 | 36篇 |
1994年 | 24篇 |
1993年 | 41篇 |
1992年 | 30篇 |
1991年 | 13篇 |
1990年 | 22篇 |
1989年 | 24篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 21篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 14篇 |
1978年 | 19篇 |
1977年 | 16篇 |
1976年 | 19篇 |
1975年 | 6篇 |
1974年 | 9篇 |
排序方式: 共有1518条查询结果,搜索用时 15 毫秒
101.
P2U/2Y-receptors elicit multiple signaling in Madin-Darby canine kidney (MDCK) cells, including a transient increase of [Ca2+]i, activation of phospholipases C (PLC) and A2 (PLA2), protein kinase C (PKC) and mitogen-activated protein kinase (MAPK). This study examines the involvement of these signaling pathways in the inhibition of Na+,K+,Cl- cotransport in MDCK cells by ATP. The level of ATP-induced inhibition of this carrier ( approximately 50% of control values) was insensitive to cholera and pertussis toxins, to the PKC inhibitor calphostin C, to the cyclic nucleotide-dependent protein kinase inhibitors, H-89 and H-8 as well as to the inhibitor of serine-threonine type 1 and 2A phosphoprotein phosphatases okadaic acid. ATP led to a transient increase of [Ca2+]i that was abolished by a chelator of Ca2+i, BAPTA. However, neither BAPTA nor the Ca2+ ionophore A231287, or an inhibitor of endoplasmic reticulum Ca2+-pump, thapsigargin, modified ATP-induced inhibition of Na+,K+, Cl- cotransport. An inhibitor of PLC, U73122, and an inhibitor of MAPK kinase (MEK), PD98059, blocked ATP-induced inositol-1,4, 5-triphosphate production and MAPK phosphorylation, respectively. However, these compounds did not modify the effect of ATP on Na+,K+, Cl- cotransport activity. Inhibitors of PLA2 (AACOCF3), cycloxygenase (indomethacin) and lypoxygenase (NDGA) as well as exogenous arachidonic acid also did not affect ATP-induced inhibition of Na+,K+,Cl- cotransport. Inhibition of the carrier by ATP persisted in the presence of inhibitors of epithelial Na+ channels (amiloride), Cl- channels (NPPB) and Na+/H+ exchanger (EIPA) and was insensitive to cell volume modulation in anisosmotic media and to depletion of cells with monovalent ions, thus ruling out the role of other ion transporters in purinoceptor-induced inhibition of Na+,K+,Cl- cotransport. Our data demonstrate that none of the known purinoceptor-stimulated signaling pathways mediate ATP-induced inhibition of Na+,K+,Cl- cotransport and suggest the presence of a novel P2-receptor-coupled signaling mechanism. 相似文献
102.
V Mooser A Maillard C Bonny M Steinmann P Shaw DP Yarnall DK Burns DF Schorderet P Nicod G Waeber 《Canadian Metallurgical Quarterly》1999,55(2):202-208
Islet-brain 1 (IB1), a regulator of the pancreatic beta-cell function in the rat, is homologous to JIP-1, a murine inhibitor of c-Jun amino-terminal kinase (JNK). Whether IB1 and JIP-1 are present in humans was not known. We report the sequence of the 2133-bp human IB1 cDNA, the expression, structure, and fine-mapping of the human IB1 gene, and the characterization of an IB1 pseudogene. Human IB1 is 94% identical to rat IB1. The tissue-specific expression of IB1 in human is similar to that observed in rodent. The IB1 gene contains 12 exons and maps to chromosome 11 (11p11.2-p12), a region that is deleted in DEFECT-11 syndrome. Apart from an IB1 pseudogene on chromosome 17 (17q21), no additional IB1-related gene was found in the human genome. Our data indicate that the sequence and expression pattern of IB1 are highly conserved between rodent and human and provide the necessary tools to investigate whether IB1 is involved in human diseases. 相似文献
103.
This study was undertaken to investigate the possible association between thrombosis and infection using an in vitro test model in which fresh bovine blood was recirculated through test conduits (3.5 mm inner diameter) containing stent-like devices. Anticoagulation was adjusted so that the recirculating blood deposited thrombi on the stent to cause gradual occlusion, thus impeding the flow. Four stent-like devices were placed in separate conduits in each experiment, and blood was recirculated with the help of pneumatically driven ventricles. Flow through these conduits was monitored by ultrasonic flow detection. To quantitate bacterial interaction with thrombi, Staphylococcus epidermidis (15E10(9)) was labeled with 111Indium-oxine and added to the blood. Experiments lasted until the flow in the test conduits dropped to 10% of the starting flow. During this recirculation, as flow gradually decreased, one stent was taken out when flow was still at 100%, the second at 75%, the third at 50%, and the fourth at 10% of the starting flow. The number of bacteria associated with the thrombus was measured by gamma counting. The following observations were made: 1) the amount of thrombus increased with time in all experiments (this was confirmed in separate experiments by using autologous 111Indium labeled platelets); 2) bacterial adhesion showed a concomitant increase as thrombus size increased (this was confirmed by using 111Indium labeled bacteria), and 3) bacterial incorporation into the thrombus occurred regardless of whether they were viable or pretreated with the antibiotic rifampin. These observations suggest that as thrombi develop, they may preferentially attract micro-organisms. This suggests that devices with adherent thrombi may have greater susceptibility for infection. 相似文献
104.
OBJECTIVE: To evaluate the effect of preoperative localization studies on the surgical management of patients with primary hyperparathyroid disease (PHPT). SUMMARY BACKGROUND DATA: Reported cure rates of initial surgical exploration for PHPT are close to 95%. Preoperative localization studies are frequently obtained to improve surgical success and decrease operative time. METHODS: Initial cervical exploration was performed in 113 patients with PHPT from 1981 to 1993. Twenty-four patients (21%) had surgery without preoperative localization studies. The remaining 89 patients (79%) had 132 noninvasive preoperative localization studies. Success of the localization studies in tumor localization, pathologic findings, postoperative serum calcium levels, and operative times were compared. Patient costs of the studies were calculated. RESULTS: Disease was identified during operation in 23 of 24 patients (96%) having cervical exploration without preoperative localization studies, and they had normal calcium levels after surgery. Eighty-seven of 89 patients (98%) having preoperative localization studies were surgically cured. The highest sensitivity rate (60%) and highest positive predictive value (79%) of the localization studies were found with thallium-technetium scintiscanning. Average cost of the localization studies was $901 per patient. Combination studies were obtained in 32 patients at an average cost of $1,314 per patient without improving sensitivity. Mean operating time did not differ for localized and nonlocalized patients. CONCLUSIONS: Preoperative localization studies did not improve parathyroid localization or cure rate and did not substantially shorten operating time in initial cervical exploration for PHPT. The economic burden of routine preoperative localization studies in these patients is not justified. 相似文献
105.
Burns Michelle Nicole; Siddique Juned; Fokuo J. Konadu; Mohr David C. 《Canadian Metallurgical Quarterly》2010,55(3):255
Objective: Anxiety is highly comorbid with depression, but little is known about the impact of anxiety disorders on the effectiveness of empirically supported psychotherapies for depression. We examined such outcomes for people with Multiple Sclerosis (MS) and depression, with versus without comorbid anxiety disorders. Design: Participants with MS (N = 102) received 16 weeks of telephone-administered psychotherapy for depression and were followed for one year post-treatment. Results: Participants with comorbid anxiety disorders improved to a similar degree during treatment as those without anxiety disorders. Outcomes during follow-up were mixed, and thus we divided the anxiety diagnoses into distress and fear disorders. The distress disorder (GAD) was associated with elevated anxiety symptoms during and after treatment. In contrast, fear disorders (i.e., panic disorder, agoraphobia, social phobia, specific phobia) were linked to depression, specifically during follow-up, across 3 different measures. Conclusions: People with GAD receiving treatment for depression may benefit from additional services targeting anxiety more specifically, while those with comorbid fear disorders may benefit from services targeting maintenance of gains after treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Burns John W.; Kubilus Amanda; Bruehl Stephen; Harden R. Norman; Lofland Kenneth 《Canadian Metallurgical Quarterly》2003,71(1):81
Changes in maladaptive cognitions may constitute therapeutic processes of multidisciplinary pain programs. A cross-lagged panel design was used to determine whether (a) early-treatment cognitive change predicted late-treatment outcome index change, but not vice versa; and (b) these effects remained significant with depression change controlled. Ninety chronic pain patients, in a 4-week multidisciplinary program, completed measures of catastrophizing, pain helplessness, depression, pain, interference, and activity level at pre-, mid-, and posttreatment. With depression changes controlled, early-treatment catastrophizing and pain helplessness changes predicted late-treatment outcome index changes, but not vice versa; early-treatment depression changes predicted late-treatment activity changes, but not vice versa. Findings advance understanding of pain treatment process and suggest that negative cognition changes may indeed affect improvements in treatment outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
Burns G. Leonard; Gomez Rapson; Walsh James A.; de Moura Marcela Alves 《Canadian Metallurgical Quarterly》2003,15(1):118
G. J. DuPaul (see record 2003-02033-012) offered two suggestions for additional research to understand the strong source effects reported by R. Gomez, G. L Burns, J. A. Walsh, and M. A. de Moura (see record 2003-02033-001) in attention-deficit/ hyperactivity disorder (ADHD) rating scales. The first suggestion was to determine whether the source effects represent mostly bias or accuracy. The second suggestion was to minimize source effects through the development of better ADHD rating scales. Because source effects can represent bias or accuracy, it is important to minimize the bias aspect through content validation procedures prior to attempts to determine whether source effects better reflect bias or accuracy. This comment offers various suggestions to reduce the bias in ADHD rating scales. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
108.
Many of the nation's homeless people suffer from unrecognized mental illnesses and do not have access to the kind of disability benefits they would be entitled to when properly assessed. The current system of disability evaluations for Social Security income claims is frequently inadequate and leaves these individuals without any source of income, health insurance, and mental health treatment. This article introduces a model of providing psychological assessments for homeless, mentally ill individuals by supervised student examiners, a model that could be replicated by other psychologists and training institutions. The authors argue that there may be a large number of homeless adults who suffer from disabling mental conditions but who are not properly diagnosed and, therefore, do not qualify for benefits. The authors propose that the model presented can help to fill a gap in services and may serve as a model of socially relevant clinical training. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
BACKGROUND: Hepatic lesions in sickle cell disease have been studied essentially in autopsy series. Previous reports on living patients are rare and concern a limited number of cases. The aim of the present study is to report the clinical, biochemical, and hepatic histological findings in 26 living patients with sickle cell disease and hepatobiliary disease. PATIENTS AND METHODS: Twenty-six of 510 patients with sickle cell disease, in whom liver tissue was available for histological analysis, were selected. In 21 patients, biopsy was obtained during laparotomy for cholecystectomy; 5 patients underwent needle biopsy for hepatomegaly and/or liver test abnormalities. RESULTS: Twenty of the 21 cholecystectomized patients, as well as the 5 other patients, had liver vascular lesions consisting of sinusoidal dilatation (23 cases), perisinusoidal fibrosis (19 cases), and acute ischemic necrosis (5 cases). It is of interest that the 21 cholecystectomized patients had clinical signs of complicated cholelithiasis, and that 20 of them had gallbladder stones, with common bile duct lithiasis in only 1 case. In the 25 patients without common bile duct obstruction, symptoms might have been due to vascular lesions, but it must also be noted that in the cholecystectomized patients they did not persist or recur following surgery. In one cirrhotic patient, marked sinusoidal lesions might have favored severe hepatocellular failure that led to liver transplantation. In another patient, fatal hepatocellular insufficiency was possibly due to ischemia. The nonvascular lesions that were observed, ie, chronic persistent or mildly active hepatitis (11 cases) and cirrhosis (2 cases), were always associated with vascular lesions. CONCLUSION: These results suggest that in sickle cell disease: (1) hepatic lesions are mainly vascular; (2) these lesions can be responsible for acute and/or chronic ischemia that may be severe; (3) symptoms suggestive of acute cholecystitis and/or biliary tract obstruction might be, at least in part, explained by vascular lesions; and (4) biliary tract surgery indications should be considered more carefully. 相似文献
110.
Castonguay Louis G.; Schut Alexander J.; Aikens Deane E.; Constantino Michael J.; Laurenceau Jean-Philippe; Bologh Laura; Burns David D. 《Canadian Metallurgical Quarterly》2004,14(1):4
This study is a preliminary investigation of an integrative treatment aimed at improving the efficacy of cognitive therapy (CT) for depression. The development of the treatment protocol was based on process findings, which suggested that strategies used in CT to resolve alliance ruptures may actually exacerbate problems in the therapeutic relationship. The protocol integrates, within the traditional CT treatment manual, procedures to repair alliance ruptures that are derived from or consistent with humanistic and interpersonal therapies. Although conducted by inexperienced therapists, the integrative treatment led to greater improvement than a waiting-list condition. The results also compare favorably to previous findings for CT. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献