全文获取类型
收费全文 | 1510篇 |
免费 | 2篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 7篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
轻工业 | 17篇 |
无线电 | 1篇 |
一般工业技术 | 6篇 |
冶金工业 | 1469篇 |
原子能技术 | 2篇 |
自动化技术 | 6篇 |
出版年
2022年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 1篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 4篇 |
1999年 | 32篇 |
1998年 | 385篇 |
1997年 | 248篇 |
1996年 | 156篇 |
1995年 | 87篇 |
1994年 | 80篇 |
1993年 | 75篇 |
1992年 | 12篇 |
1991年 | 34篇 |
1990年 | 28篇 |
1989年 | 30篇 |
1988年 | 36篇 |
1987年 | 34篇 |
1986年 | 18篇 |
1985年 | 18篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 16篇 |
1978年 | 5篇 |
1977年 | 43篇 |
1976年 | 90篇 |
1975年 | 4篇 |
1968年 | 1篇 |
1962年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1512条查询结果,搜索用时 7 毫秒
991.
Z Yang R Youil D Thorburn CW Chow RG Cotton GS Baldwin 《Canadian Metallurgical Quarterly》1997,20(6):828-830
Occupational exposures were assessed in a case-control study on testicular cancer using self-administered questionnaires. In total, answers were obtained for 148 (91%) cases and 315 (87%) controls. Of the cases, 101 had seminoma and 47 had embryonal testicular cancer. An increased odds ratio (OR) was found for exposure to polyvinyl chloride (PVC) yielding an OR of 6.6 (95% confidence interval, 1.4-32). The risk increased further if cases with self-reported cryptorchidism or orchitis were excluded. Six of the 7 exposed cases had seminoma. Exposure to other types of plastics did not significantly increase the risk of testicular cancer. 相似文献
992.
Anticoagulants are widely used in the prevention of thromboembolic disease (particularly during the postoperative period) and in the curative treatment of deep vein thromboses. Two classes of anticoagulants are currently available: heparins (standard heparin, low molecular weight heparin) and coumarin anticoagulants. The choice of anticoagulant must take into account the clinical context (preventive or curative treatment), as well as the pharmacological and pharmacokinetic properties of the anticoagulant. This treatment requires laboratory monitoring adopted to the anticoagulant selected. 相似文献
993.
The therapeutic options for the treatment of epilepsy have expanded during the 1990s. Since 1993, four novel agents (felbamate, gabapentin, lamotrigine, and topiramate) have been approved by the US Food and Drug Administration, primarily for adjunctive treatment of partial seizures. In addition, a water-soluble pro-drug of phenytoin, fosphenytoin, and a sustained-release preparation of carbamazepine have been introduced. The novel anticonvulsants represent a potential improvement for patients whose seizures are incompletely controlled or who experience significant adverse effects with older anticonvulsants. Felbamate, lamotrigine, and topiramate appear to have a broad spectrum of action in seizure control, but felbamate use is limited by the potential for serious adverse effects. Gabapentin, lamotrigine, and topiramate are all well tolerated. Gabapentin has no known drug interactions, whereas lamotrigine and topiramate have limited interactions compared with older agents. The sustained-release preparation of carbamazepine may decrease the incidence of adverse effects and increase patient compliance. Fosphenytoin offers a safer method for intravenous administration of phenytoin and the added flexibility of intramuscular administration. Taken together, these recent advances in treatment may bring about improved efficacy and decreased adverse effects for many patients with epilepsy. 相似文献
994.
995.
The widespread expression of CD40 in normal epithelial cells and carcinoma cells suggests that this receptor has important, additional influences beyond that of regulating immune responses. Here, Lawrence Young and colleagues discuss the effect of CD40 ligation on epithelial cells and consider the role of this pathway in the pathogenesis and treatment of carcinomas. 相似文献
996.
Male offspring, which cannot reproduce independently, represent a cost of sexual reproduction. This cost is eliminated by the production of hermaphroditic offspring in the self-fertilizing nematode Caenorhabditis briggsae. However, these hermaphrodites can outcross by mating with males. Half the sperm received from males contain no sex chromosome and therefore give rise to male progeny. Mating with males should thus impose the cost of making male offspring. We found that male sperm took immediate precedence over hermaphrodite sperm, resulting in maximized outcrossing, but the appearance of male progeny was delayed after mating. This delay is caused by the male X-bearing sperm outcompeting their nullo-X counterparts. The competitive advantage of X-bearing sperm over nullo-X sperm is limited to sperm from males; it did not occur in a mutant hermaphrodite that produces both types of sperm. The chromosomal effect on sperm competitiveness in C. briggsae, which has not been observed in other species, suggests that the X chromosome has evolved a form of meiotic drive, selfishly increasing the competitiveness of sperm that bear it over those that do not. Thus, the multiple levels of sperm competitiveness found in C. briggsae maximize outcrossing after mating while delaying the cost of making male offspring. 相似文献
997.
G Niedobitek E Kremmer H Herbst L Whitehead CW Dawson E Niedobitek C von Ostau N Rooney FA Gr?sser LS Young 《Canadian Metallurgical Quarterly》1997,90(4):1664-1672
We describe two new monoclonal antibodies specific for the Epstein-Barr virus (EBV)-encoded latent membrane protein 2A (LMP2A) that are suitable for the immunohistochemical analysis of routinely processed paraffin sections. These antibodies were applied to the immunohistochemical detection of LMP2A in Hodgkin's disease (HD). LMP2A-specific membrane staining was seen in the Hodgkin and Reed-Sternberg (HRS) cells of 22 of 42 (52%) EBV-positive HD cases, but not in 39 EBV-negative HD cases. In lymphoid tissues from patients with acute infectious mononucleosis (IM), interfollicular immunoblasts were shown to express LMP2A. This is the first demonstration of LMP2A protein expression at the single-cell level in EBV-associated lymphoproliferations in vivo. The detection of LMP2A protein expression in HD and IM is of importance in view of the proposed role of this protein for maintaining latent EBV infection and its possible contribution for EBV-associated transformation. Because LMP2A provides target epitopes for EBV-specific cytotoxic T cells, the expression of this protein in HRS cells has implications for the immunotherapeutic approaches to the treatment of HD. 相似文献
998.
A 34-year-old man came to this Emergency Room because of fever, swelling and pain in the right thigh. Tetralogy of Fallot with bicuspid pulmonary valve was diagnosed after serial examination, and computed tomography of the right thigh revealed pyogenic myositis. Surgical drainage of the right thigh abscess and a further pus culture yielded viridans streptococci. There has been no record in the medical literature of a pyogenic myositis caused by viridans streptococci in an adult tetralogy of Fallot. This is thus the first case reported. 相似文献
999.
CW Trotter 《Canadian Metallurgical Quarterly》1997,11(1):52-64
Management of ductal carcinoma in situ has become one of the most controversial topics in breast disease. While mastectomy has been the traditional treatment, many now feel it is excessive in most cases. As a result, a great effort has been made to identify pathobiological characteristics of DCIS that can be used to stratify appropriate treatment decisions. This article reviews efforts to relate pathobiological characteristics to disease management and provides treatment recommendations based on the latest evidence. 相似文献
1000.
OBJECTIVE: To compare fragment reconstruction and bone plate fixation versus bridging plate fixation for treating highly comminuted (> 4 fragments) femoral fractures in dogs. DESIGN: Retrospective study. ANIMALS: 35 dogs with highly comminuted fractures of the femur. PROCEDURE: Medical records of all dogs included in this study were reviewed. Dogs had been treated with fragment reconstruction and bone plate application (n = 20) or major fragment alignment and bridging plate fixation (15). Postoperative and follow-up radiographs were evaluated. Operating and hospitalization times, bone alignment, bone healing, and complications were considered. RESULTS: There were no differences in hospitalization times, limb alignment, and complications between dogs with fractures treated with fragment reconstruction and dogs with fractures treated with bridging plate fixation. Dogs with fractures treated with bridging plate fixation had shorter operative times and faster times to radiographic evidence of bone healing. CLINICAL IMPLICATIONS: Bridging plate fixation is quicker to perform and results in faster healing than fragment reconstruction and bone plate fixation when used to treat comminuted femoral fractures. 相似文献