首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1257篇
  免费   6篇
  国内免费   2篇
化学工业   57篇
金属工艺   2篇
机械仪表   2篇
建筑科学   19篇
能源动力   7篇
轻工业   56篇
无线电   19篇
一般工业技术   46篇
冶金工业   1019篇
自动化技术   38篇
  2022年   7篇
  2021年   6篇
  2020年   3篇
  2019年   7篇
  2018年   5篇
  2017年   6篇
  2016年   3篇
  2015年   3篇
  2014年   8篇
  2013年   14篇
  2012年   20篇
  2011年   11篇
  2010年   10篇
  2009年   6篇
  2008年   9篇
  2007年   10篇
  2006年   11篇
  2005年   10篇
  2004年   17篇
  2003年   9篇
  2002年   6篇
  2001年   7篇
  2000年   9篇
  1999年   39篇
  1998年   311篇
  1997年   188篇
  1996年   127篇
  1995年   69篇
  1994年   52篇
  1993年   61篇
  1992年   12篇
  1991年   12篇
  1990年   11篇
  1989年   9篇
  1988年   12篇
  1987年   14篇
  1986年   9篇
  1985年   13篇
  1984年   2篇
  1983年   3篇
  1982年   9篇
  1981年   6篇
  1980年   15篇
  1978年   4篇
  1977年   19篇
  1976年   63篇
  1975年   1篇
  1974年   2篇
  1973年   3篇
  1955年   2篇
排序方式: 共有1265条查询结果,搜索用时 23 毫秒
181.
PURPOSE: To determine whether recombinant human interleukin-3 (rhIL-3) reduces bone marrow depression and improves chemotherapeutic schedule adherence in ovarian cancer patients receiving first-line combination chemotherapy. PATIENTS AND METHODS: In a randomized multicenter study, 185 patients received carboplatin (dose based on projected area under the concentration-time curve [AUC]=4) and cyclophosphamide (750 mg/m2) day 1, every 3 weeks for six cycles. Patients were randomized to receive rhIL-3 (5 microg/kg) or placebo once daily subcutaneously on days 3 to 12. RESULTS: Adherence to chemotherapeutic regimen, mean chemotherapy cycle length, tumor response rate, and median survival at 24 months did not differ between groups. The number of side effects-primarily allergic reactions, flu-like symptoms and fever-were higher in the rhIL-3 group, which resulted in 21 discontinuations compared with one in the placebo group. Compared with placebo, the rhIL-3 group had higher platelet counts day 1 of cycles 2 to 6. The number of patients with World Health Organization (WHO) grade IV thrombocytopenia or number of platelet transfusions did not differ. Leukocyte counts differed only in cycles 1 and 2 between groups. The leukocyte nadir occurred earlier in the rhIL-3 (day 12) than in the placebo group (day 15, P=.006). Leukocytes and neutrophils were only higher in the rhIL-3 group day 1 of cycle 2. In cycles 4 and 5, more patients with WHO grade IV neutropenia received rhIL-3 (P < .005). Eosinophil counts were higher day 1 of cycles 2 to 6 in the rhIL-3 group (P < .0001). CONCLUSION: rhIL-3 had stimulatory hematopoietic effects. This did not result either in reduction of platelet transfusions or in improvement of chemotherapeutic schedule adherence. There were more side effects in the rhIL-3 group than in the placebo group. rhIL-3 at 5 microg/kg/d is, therefore, not of clinical benefit in this chemotherapeutic regimen.  相似文献   
182.
183.
We report a case of myelodysplastic syndrome (MDS) with myelofibrosis and pulmonary tuberculosis who had marked basophilia in the peripheral blood. A clonal karyotypic abnormality characterized by trisomy 8 was demonstrated by cytogenetic analysis. By correlation of cell morphology with results of fluorescence in situ hybridization using a chromosome 8 probe, we demonstrated that the basophils were not reactive but belonged to the neoplastic MDS clone.  相似文献   
184.
Testicular germ cell tumour is said to be a model for curable neoplasm. However, the prognosis of primary extragonadal germ cell tumour does not appear to be as promising. Though similar in histology, the biology of primary extragonadal germ cell tumour is different as exemplified by the patients in this review. Eight patients with primary mediastinal germ cell tumours were treated with intensive cisplatin-based chemotherapy. All, except one, had non-seminomatous components. The poor prognosis of mediastinal germ cell tumour is due to a combination of poor treatment results with the cisplatin-based regimen and the development of non-germ cell and haematological malignancies.  相似文献   
185.
A novel, time- and BMP-saving in vitro method for the detection and quantitation of bone morphogenetic protein (BMP) activity was developed based on the measurable effects of BMP on rat skeletal muscle myoblasts (L6). Calcium incorporation, stimulation of alkaline phosphatase activity and production of osteocalcin were used as markers of bone cell metabolism and on-going morphogenesis. The morphological change was confirmed by Chlorantine fast red and von Kossa staining. The response of various BMPs was purity-dependent and consistent with intramuscular implantations of the same materials. Neither TGF-beta1 nor insulin could induce the same actions. The data from this study indicate that at least in part in vivo implantations of BMP extracts can be replaced by in vitro measurement of osteoinductivity. Considerable saving of time, BMP and experimental animals can be achieved using cell culture conditions for the determination of bone-forming activity.  相似文献   
186.
In this prospective study of thyroid catecholamine interactions, 15 severely burned patients were divided into two groups. Nine patients receiving 200 micrograms/day of triiodothyronine constituted the T3-treated group. Eight additional patients constituted the untreated group. Mean serum concentrations of T3 were significantly lower in the untreated group than in the treated group. Mean serum thyroxine (T4) concentrations were significantly higher in the untreated group than in the treated group. The mean plasma norepinephrine concentration in the untreated group was significantly greater than that of the treated group. In the untreated group, log plasma norepinephrine correlated inversely with serum T3. Similarly, in the untreated group, log plasma epinephrine correlated inversely with serum T3. Metabolic rates were not different between groups. These data suggest that a reciprocal relationship exists between plasma concentration of T3 and both norepinephrine and epinephrine in untreated burn patients and that treatment with the metabolically active hormone, triiodothyronine, does not alter the level of hypermetabolism accompanying thermal injury.  相似文献   
187.
Confusion about the cost-effectiveness of case management stems partly from poorly defined assumptions about outcomes and unclear theories of how case management affects costs. The authors discuss how cost-effectiveness is influenced by the characteristics of various case management models, characteristics of the clients served, and contextual factors, including resources available in the treatment system and financial incentives built into various payment mechanisms. Important differences exist between case management models in the mechanisms favored for managing resources, including whether the client or the case manager is primarily responsible for directing the course of treatment, whether reduction in hospitalizations is a primary goal, whether team case management is used, and how the size of caseloads is determined.  相似文献   
188.
OBJECTIVE: We determined whether the prostaglandin inhibitor sulindac crosses the human placenta. METHODS: The recirculating single-cotyledon placenta model was used to characterize the maternal-to-fetal and fetal-to-maternal transport of 14C-labeled sulindac in normal term placentas perfused immediately after delivery. Antipyrine was added as a standard for simple diffusion. Serial samples were taken from both reservoirs during each 3-hour perfusion. Transport was calculated using liquid scintillation spectrometry for 14C-labeled sulindac and high-performance liquid chromatography for antipyrine. RESULTS: There was significant maternal-to-fetal transfer of sulindac. The mean (+/- SD) transfer at 2 hours was 7.22 +/- 2.57%. The fetal-to-maternal transfer was similar at 10.75 +/- 3.80%. The mean maternal/fetal concentration ratio of sulindac was 0.42 at 3 hours. Placental uptake ranged from 24-45 ng/g of placenta. CONCLUSIONS: Sulindac crosses the human placenta in small but significant amounts. The transport is similar in both directions, implying simple diffusion.  相似文献   
189.
We report the occurrence of cutaneous sarcoid-like granulomas in one patient with common variable immunodeficiency and another with 'thymoma and hypogammaglobulinaemia'. To our knowledge, this is the first time that such skin lesions have been described in patients with primary immunodeficiency. These granulomas may be attributed to a combination of interleukin-2 deficiency and a profound CD4 lymphopenia. The lesions are similar to the non-infectious 'papular eruption' associated with human immunodeficiency virus infection, and might reflect a common pathogenic mechanism.  相似文献   
190.
At fertilization, the membrane potential of the egg of the lamprey, Lampetra japonica, shifted rapidly from its resting value of -12 to +36 mV and gradually returned to about the same resting level (fertilization potential). The amplitude of depolarization was influenced by the external Cl- concentration and by an anion channel blocker, DIDS, indicating that the positive shift of membrane potential resulted from Cl- efflux. A similar change in membrane potential (activation potential) was observed when the unfertilized egg was pricked with a fine needle or treated with A23187 to induce parthenogenetic activation. Pricking at the animal pole region (predetermined site for sperm entry) resulted in the occurrence of an immediate activation potential and the initiation of cortical granule exocytosis. A time lag between the pricking and the occurrence of the activation potential was observed when the egg was pricked at a distance from the animal pole. In this instance, the activation potential was produced immediately before the propagating cortical granule exocytosis initiated at the pricked site reached the animal pole region. Sperm-egg fusion was blocked in eggs voltage-clamped at +20 to +40 mV and inseminated, whereas it took place in eggs clamped at -60 to 0 mV. However, most eggs clamped at +20 to +40 mV did activate, indicating that the voltage dependence of egg activation differs from that of sperm-egg fusion. Although eggs voltage-clamped at negative membrane potentials permitted multiple sperm to fuse with the egg plasma membrane, the nucleus of the fused sperm did not necessarily enter the ooplasm. We conclude that: (1) A fast electrical block against polyspermy operates in this species and is effective for about 160 sec of the onset of the positive shift; (2) the opening of Cl- channels is responsible for the potential change; (3) the channels are largely localized in the animal pole region; (4) during voltage clamp at positive potentials, eggs can be activated without sperm-egg fusion; and (5) during voltage clamp at negative potentials, sperm-egg fusion occurs, but sperm entry into the egg cytoplasm does not always proceed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号