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   4747篇
  免费   295篇
  国内免费   17篇
耳鼻咽喉   32篇
儿科学   190篇
妇产科学   103篇
基础医学   780篇
口腔科学   64篇
临床医学   343篇
内科学   834篇
皮肤病学   73篇
神经病学   347篇
特种医学   89篇
外科学   489篇
综合类   115篇
一般理论   5篇
预防医学   379篇
眼科学   164篇
药学   543篇
中国医学   73篇
肿瘤学   436篇
  2023年   35篇
  2022年   86篇
  2021年   119篇
  2020年   86篇
  2019年   109篇
  2018年   134篇
  2017年   97篇
  2016年   111篇
  2015年   142篇
  2014年   158篇
  2013年   261篇
  2012年   348篇
  2011年   348篇
  2010年   211篇
  2009年   156篇
  2008年   267篇
  2007年   240篇
  2006年   283篇
  2005年   223篇
  2004年   182篇
  2003年   152篇
  2002年   159篇
  2001年   106篇
  2000年   108篇
  1999年   70篇
  1998年   44篇
  1997年   29篇
  1996年   18篇
  1995年   18篇
  1994年   18篇
  1993年   17篇
  1992年   55篇
  1991年   58篇
  1990年   46篇
  1989年   55篇
  1988年   38篇
  1987年   33篇
  1986年   30篇
  1985年   35篇
  1984年   27篇
  1983年   30篇
  1982年   16篇
  1981年   15篇
  1980年   21篇
  1979年   34篇
  1978年   18篇
  1977年   23篇
  1974年   16篇
  1972年   15篇
  1967年   14篇
排序方式: 共有5059条查询结果,搜索用时 15 毫秒
1.
2.
BACKGROUND: Penetrating injuries of the perineum are rare but very dangerous. Since the genitourinary and colorectal organs may be injured, how to evaluate surgical management of the injury is very important.METHODS: The present report presents a case of penetrating injury of the perineum by a wooden stick when the patient fell on the upright wooden stick from a tree. The three feet long stick entered the perineal region just left lateral to the anal opening. Upon reaching the thoracic cavity, it broke and only a foot stick was left in the subcutaneous plane. These injuries are potentially serious with risk of damage to multiple organs. Exploratory laprotomy was done, and bladder injury was repaired. The entry wound and the track of stick was thoroughly washed and allowed for secondary intention healing.RESULTS: The post operative period was uneventful and the patient recovered fully.CONCLUSION: Meticulous evaluation and surgical management of perineal injuries are the key to prevent devastating complications.  相似文献   
3.
A rare case of an advanced primary broad ligament carcinoma is discussed, with a review of the literature regarding its incidence, presentation and management. This patient showed a complete response to adjuvant cisplatin-based chemotherapy following panhysterectomy and is presently without any evidence of disease, 15 months after completion of her treatment.  相似文献   
4.
Supplementation of the diet of adult male rats with 4,000 ppm zinc as ZnSO4 for 30 to 32 days increased the zinc content in the testis and sperm by 25 and 18 per cent respectively, but did not change the same in accessory reproductive tissues, e.g. epididymis, seminal vesicle and prostate. The incidence of conception from mating between normal females and zinc fed males was lower as compared to mating between normal females and control males. This observation indicated reduced fertility of the males resulting from additional zinc ingestion. Motility of the sperm collected from the epididymis (tail) of the zinc treated rats was found to be inhibited. It has been suggested that excess zinc in the sperm was responsible for their poor motility and hence a reduced fertilising capacity.  相似文献   
5.
The methanolic fraction of P. indica root extract was found to possess significant antiulcer activity in different experimental animal models. In preventive antiulcer tests, significant protective actions in acetylsalicylic acid, serotonin and indomethacin-induced gastric lesions were observed in experimental rats. The extract also afforded significant protection to chemically-induced duodenal lesion in guineapigs. Significant enhancement of healing process in acetic acid-induced chronic gastric lesions were also observed in the extract-treated animals.  相似文献   
6.
A case report of a male aged 31 who, after a journey to Bangladesh, returned with a disease resembling acute hepatitis A. Closer study revealed a hepatitis E infection. He recovered in slightly over two weeks.  相似文献   
7.
Human lymphoproliferative diseases can be hypothesized to invade locally and to metastatize via mechanisms similar to those developed by a variety of solid tumors, i.e., the secretion of extracellular matrix-degrading enzymes and stimulation of angiogenesis. To assess this hypothesis, Namalwa, Raji, and Daudi cell lines (Burkitt’s lymphoma), LIK and SB cell lines (B-cell lymphoblastic leukemia), CEM and Jurkat cell lines (T-cell lymphoblastic leukemia), and U266 cell line (multiple myeloma) were evaluated for their capacity to produce matrix metalloproteinase-2 and -9, and urokinase-type plasminogen activator. These cell lines were also assessed for their ability: (1) to produce the angiogenic basic fibroblast growth factor and vascular endothelial growth factor; (2) to induce an angiogenic phenotype in cultured endothelial cells, represented by cell proliferation, chemotaxis, and morphogensis; (3) to stimulate angiogenesis in different in vivo experimental models. All cell lines expressed the mRNA for one or both metalloproteinases. Namalwa, Raji, LIK, SB, and U266 cells secreted the active form of both metalloproteinases, while Daudi, CEM, and Jurkat cells produced metalloproteinase-2 but not -9. In contrast, urokinase-type plasminogen activator was secreted only by SB cells. While Raji, LIK, SB, CEM, and Jurkat cells secreted both basic fibroblast growth factor and vascular endothelial growth factor, Daudi and U266 cells produced only the former, and Namalwa cells only the latter. Accordingly, the conditioned medium of all cell lines stimulated cell proliferation and/or chemotaxis in cultured endothelial cells, with the exception of that of Namalwa cells which was ineffective. The conditioned medium of CEM and Jurkat cells induced morphogenesis in cultured endothelial cells grown on a reconstituted basement membrane (Matrigel). Lastly, Namalwa, Raji, LIK, SB, U266, CEM, and Jurkat cells induced angiogenesis and mononuclear cell recruitment in the murine Matrigel sponge model and in a chick embryo chorioallantoic membrane assay. The extent of angiogenesis in both models was strictly correlated with the density of the mononuclear cell infiltrate. The results indicate that human lymphoproliferative disease cells possess both local and remote invasive ability via the secretion of matrix-degrading enzymes and the induction of angiogenesis which is fostered by host inflammatory cells and by an intervening ensemble of angiogenic factors.  相似文献   
8.
Radiosynthesis of 2'-deoxy-2'-[(18)F]-fluoro-5-methyl-1-beta-L-arabinofuranosyluracil ([(18)F]-L-FMAU) is reported. Compound 1 was synthesized and converted to 2-triflate 2. Compound 3 was prepared from 2 using tetrabutylammonium[(18)F]fluoride, converted to 4, and then coupled with 5. The crude product was hydrolyzed, and purified by HPLC to obtain 7a. The radiochemical yield of [(18)F]-L-FMAU was 26% decay corrected (d.c.) in four runs with radiochemical purity >99% and specific activity 2200 mCi/micromol. The synthesis time was 3.3-3.5h from the end of bombardment (EOB).  相似文献   
9.
10.
Mirror movements (MM) occur in early, asymmetric Parkinson's disease (PD). To examine the pathophysiology of MM in PD, we studied 13 PD patients with MM (PD-MM), 7 PD patients without MM (PD-NM), and 14 normal subjects. Cross-correlogram did not detect common synaptic input to motoneuron pools innervating homologous hand muscles in PD-MM patients. Transcranial magnetic stimulation studies showed no significant difference in ipsilateral motor-evoked potentials between PD-MM patients and normal subjects. The MM side of PD-MM patients showed a slower increase in ipsilateral silent period area with higher level of muscle contraction than the non-MM side and normal subjects. There was less interhemispheric inhibition (IHI) at long interstimulus intervals of 20 to 50 ms in PD-MM than PD-NM. IHI reduced short interval intracortical inhibition in normal subjects and PD-NM, but not in PD-MM. IHI significantly increased intracortical facilitation in PD-MM and PD-NM patients, but not in normal subjects. Our results suggest that MM in PD is due to activation of the contralateral motor cortex. PD-MM patients had reduced transcallosal inhibitory effects on cortical output neurons and on intracortical inhibitory circuits compared to PD-NM patients and controls. These deficits in transcallosal inhibition may contribute to MM in PD patients.  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