全文获取类型
收费全文 | 2784篇 |
免费 | 12篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 8篇 |
综合类 | 1篇 |
化学工业 | 52篇 |
金属工艺 | 7篇 |
机械仪表 | 8篇 |
建筑科学 | 19篇 |
矿业工程 | 1篇 |
能源动力 | 5篇 |
轻工业 | 32篇 |
水利工程 | 5篇 |
无线电 | 57篇 |
一般工业技术 | 40篇 |
冶金工业 | 2527篇 |
原子能技术 | 2篇 |
自动化技术 | 34篇 |
出版年
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2013年 | 23篇 |
2012年 | 15篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 11篇 |
2008年 | 16篇 |
2007年 | 18篇 |
2006年 | 7篇 |
2005年 | 13篇 |
2004年 | 13篇 |
2003年 | 16篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 4篇 |
1999年 | 74篇 |
1998年 | 828篇 |
1997年 | 437篇 |
1996年 | 295篇 |
1995年 | 165篇 |
1994年 | 122篇 |
1993年 | 155篇 |
1992年 | 22篇 |
1991年 | 22篇 |
1990年 | 26篇 |
1989年 | 29篇 |
1988年 | 26篇 |
1987年 | 30篇 |
1986年 | 27篇 |
1985年 | 20篇 |
1984年 | 2篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 12篇 |
1980年 | 19篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 54篇 |
1976年 | 158篇 |
1975年 | 3篇 |
1966年 | 4篇 |
1964年 | 2篇 |
1963年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有2798条查询结果,搜索用时 15 毫秒
121.
SJ Dowell AL Bishop SL Dyos AJ Brown MS Whiteway 《Canadian Metallurgical Quarterly》1998,150(4):1407-1417
The mating pathway of Saccharomyces cerevisiae is widely used as a model system for G protein-coupled receptor-mediated signal transduction. Following receptor activation by the binding of mating pheromones, G protein betagamma subunits transmit the signal to a MAP kinase cascade, which involves interaction of Gbeta (Ste4p) with the MAP kinase scaffold protein Ste5p. Here, we identify residues in Ste4p required for the interaction with Ste5p. These residues define a new signaling interface close to the Ste20p binding site within the Gbetagamma coiled-coil. Ste4p mutants defective in the Ste5p interaction interact efficiently with Gpa1p (Galpha) and Ste18p (Ggamma) but cannot function in signal transduction because cells expressing these mutants are sterile. Ste4 L65S is temperature-sensitive for its interaction with Ste5p, and also for signaling. We have identified a Ste5p mutant (L196A) that displays a synthetic interaction defect with Ste4 L65S, providing strong evidence that Ste4p and Ste5p interact directly in vivo through an interface that involves hydrophobic residues. The correlation between disruption of the Ste4p-Ste5p interaction and sterility confirms the importance of this interaction in signal transduction. Identification of the Gbetagamma coiled-coil in Ste5p binding may set a precedent for Gbetagamma-effector interactions in more complex organisms. 相似文献
122.
AS Lages KC Silva AL Miranda CA Fraga EJ Barreiro 《Canadian Metallurgical Quarterly》1998,8(2):183-188
OBJECTIVE: To study the effect of adjuvant chemotherapy after curative hepatic resection in patients with hepatocellular carcinoma. DESIGN: A randomized controlled trial. SETTING: A tertiary referral center. PATIENTS: During a 54-month period, 142 patients with hepatocellular carcinoma underwent hepatic resection at 1 institution. Sixty-six patients who survived the operation and had no demonstrable evidence of residual disease on ultrasonographic examination and hepatic angiographic testing at 1 month after surgery agreed to participate in the study. The median follow-up time was 28.3 months. INTERVENTION: Thirty patients received a combination of intravenous epirubicin hydrochloride (8 doses of 40 mg/m2 each at 6-week intervals) and transarterial chemotherapy using an emulsion of iodized oil and cisplatin (3 courses with a maximum dose of 20 mL each at 2-month intervals). Thirty-six patients had no adjuvant treatment. MAIN OUTCOME MEASURES: Recurrence rate and disease-free survival. RESULTS: A total of 138 courses of intravenous epirubicin was given to the 30 patients. Sixty-one courses of transarterial chemotherapy were given to only 29 of the 30 patients assigned to the treatment group, because the hepatic artery in 1 patient was thrombosed. Six patients (20%) had chemotherapy-related complications with no mortality. Twenty-three of 30 patients in the treatment group and 17 of 36 patients in the control group had recurrences (P=.01). Patients who received adjuvant chemotherapy had a higher incidence of extrahepatic metastases (11 patients vs 5 patients; P=.03). The respective disease-free survival rates at 1, 2, and 3 years were 50%,36%, and 18% for the treatment group and 69%, 53%, and 48% for the control group (P=.04). CONCLUSION: In a group of patients who underwent curative resection of hepatocellular carcinoma, postoperative adjuvant chemotherapy using the present regimen was associated with more frequent extrahepatic recurrences and a worse outcome. 相似文献
123.
AL Zietman WU Shipley DS Kaufman EM Zehr NM Heney AF Althausen FJ McGovern 《Canadian Metallurgical Quarterly》1998,160(5):1673-1677
PURPOSE: We describe a protocol designed to evaluate the use of twice daily radiation used together with cisplatin and 5 fluorouracil (5-FU) in the treatment of operable transitional cell carcinoma of the bladder with potential bladder preservation. MATERIALS AND METHODS: A total of 18 consecutive patients with T2-T4a bladder tumors underwent as complete a transurethral resection as possible, which was visibly complete in 14 cases. They then received twice daily radiation and infusion cisplatin and 5-FU during an induction phase. No therapy was given for 3 weeks, following which patients were reevaluated cystoscopically. Cases of clinical complete response by biopsy and cytology were consolidated with further chemotherapy/radiation using the same chemotherapeutic agents and radiation schedule. Patients who had incomplete responses were advised to undergo an immediate radical cystectomy. Of the 18 patients 15 subsequently received 3 cycles of adjuvant chemotherapy, consisting of methotrexate, cisplatin and vinblastine. Median followup for the entire group is 32 months. RESULTS: Of the 18 patients 14 had no detectable tumor after induction therapy. Of the 4 patients with persistent tumor 2 underwent radical cystectomy and 2 refused cystectomy, 1 of whom was treated with partial cystectomy and the other with consolidation chemotherapy/radiation. The actuarial overall survival at 3 years was 83%. The chance of a patient being alive at 3 years with a native bladder was 78%. No patient required cystectomy for hematuria or bladder shrinkage. Three patients in whom superficial tumors developed were treated successfully with bacillus Calmette-Guerin. Small bowel obstruction in 1 case was corrected surgically. CONCLUSIONS: This pilot study demonstrates a high rate of response to this combined chemotherapy/radiation regimen in conjunction with a visibly complete transurethral resection. Reevaluation after a short induction phase allows for the early selection of patients with persistent disease for radical cystectomy. 相似文献
124.
J Werner C Fernández-del Castillo JA Rivera N Kollias KB Lewandrowski DW Rattner AL Warshaw 《Canadian Metallurgical Quarterly》1998,43(3):401-407
Nucleosome dimers from chicken erythrocytes show an ionic strength dependence of sedimentation coefficient similar to that of trimers, and indicative of a degree of compaction over a range of low ionic strengths. This is not easily reconciled with straight linkers but is consistent with bending or kinking of the linker DNA. 相似文献
125.
126.
127.
The family physician occupies a front-line position in the detection and treatment of emotional problems and psychiatric illnesses. The practice pattern of the family physician necessitates an efficient, effective model of psychotherapy The BATHE technique is a brief psychotherapeutic method that addresses the patient's background issues, affect and most troubling problem. The emphasis of the interview then shifts to how the patient is handling the problem and a demonstration of empathy by the physician. Some of the challenges in psychotherapy are presented, and cases in which the BATHE technique was used are described. 相似文献
128.
129.
H Ramirez-Gil E Feldberg VM Almeida-Val AL Val 《Canadian Metallurgical Quarterly》1998,31(11):1449-1458
Karyological characteristics, i.e., diploid number, chromosome morphology and nucleolus organizer regions (NORs), biochemical characteristics, i.e., electrophoretic analysis of blood hemoglobin and the tissue enzymes lactate dehydrogenase (LDH), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), and phosphoglucose isomerase (PGI), and physiological characteristics, i.e., relative concentration of hemoglobin and intraerythrocytic concentrations of organic phosphates were analyzed for the species Callophysus macropterus collected from Marchantaria Island (white water system--Solim?es River) and Anavilhanas Archipelago (black water system--Negro River). Karyological and biochemical data did not reveal significant differences between specimens collected at the two sites. However, the relative distribution of hemoglobin bands I and III (I = 16.33 +/- 1.05 and III = 37.20 +/- 1.32 for Marchantaria specimens and I = 6.33 +/- 1.32 and III = 48.05 +/- 1.55 for Anavilhanas specimens) and levels of intraerythrocytic GTP (1.32 +/- 0.16 and 2.76 +/- 0.18 for Marchantaria and Anavilhanas specimens, respectively), but not ATP or total phosphate, were significantly different, indicating a physiological adaptation to the environmental conditions of these habitats. It is suggested that C. macropterus specimens from the two collecting sites belong to a single population, and that they adjusted some physiological characteristics to adapt to local environmental conditions. 相似文献
130.
J Bj?rheim S Lystad A Lindblom U Kressner S Westring S Wahlberg G Lindmark G Gaudernack P Ekstr?m J R?e WG Thilly AL B?rresen-Dale 《Canadian Metallurgical Quarterly》1998,403(1-2):103-112
Pefloxacin plus metronidazole versus netilmicin plus metronidazole in the prevention of nosocomial infections during contaminated surgery. Surgical prophylaxis is widely used in contaminated surgery, especially colorectal surgery. In this clinical trial the efficacy of pefloxacin 800 mg i.v. slow infusion associated to metronidazole 500 mg i.v. 1-2 hours before surgery and then metronidazole alone after 6 and 12 hours versus netilmicin 200 mg i.m. associated to metronidazole 500 mg i.v. 1-2 hours before surgery and then both after 6 and 12 hours were evaluated in 97 patients suffering by colorectal surgery. Efficacy of prophylaxis in patients was evaluated in terms of appearance of post-surgical infections (abdominal, urinary, respiratory and wound infections). In pefloxacin + metronidazole group (53 patients), two cases of wound infections (3.8%) and three cases of respiratory infections (5.8%) were observed. In netilmicin + metronidazole group (44 patients), two cases of wound infections (4.9%), three cases of urinary infections (7%), three cases of respiratory infections (7.5%) and one case of intra-abdominal infection were observed. Our data confirmed that in colorectal surgery, the association pefloxacin, drug with microbiological and pharmacokinetics characteristics suitable for prophylaxis + metronidazole, active against anaerobes pathogens, prevents post-surgical infections as well as a reference association (netilmicin + metronidazole), with the advantage of a single administration. 相似文献