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   9162篇
  免费   448篇
  国内免费   40篇
耳鼻咽喉   121篇
儿科学   174篇
妇产科学   209篇
基础医学   1265篇
口腔科学   185篇
临床医学   617篇
内科学   2002篇
皮肤病学   283篇
神经病学   685篇
特种医学   350篇
外科学   1505篇
综合类   55篇
预防医学   244篇
眼科学   133篇
药学   642篇
中国医学   24篇
肿瘤学   1156篇
  2023年   48篇
  2022年   82篇
  2021年   158篇
  2020年   95篇
  2019年   115篇
  2018年   161篇
  2017年   157篇
  2016年   138篇
  2015年   189篇
  2014年   234篇
  2013年   240篇
  2012年   402篇
  2011年   490篇
  2010年   250篇
  2009年   239篇
  2008年   402篇
  2007年   459篇
  2006年   485篇
  2005年   421篇
  2004年   405篇
  2003年   419篇
  2002年   388篇
  2001年   310篇
  2000年   354篇
  1999年   309篇
  1998年   96篇
  1997年   100篇
  1996年   90篇
  1995年   83篇
  1994年   75篇
  1993年   62篇
  1992年   213篇
  1991年   173篇
  1990年   197篇
  1989年   200篇
  1988年   187篇
  1987年   138篇
  1986年   123篇
  1985年   124篇
  1984年   96篇
  1983年   67篇
  1982年   41篇
  1979年   81篇
  1978年   55篇
  1977年   45篇
  1975年   38篇
  1974年   42篇
  1972年   39篇
  1970年   37篇
  1969年   45篇
排序方式: 共有9650条查询结果,搜索用时 31 毫秒
991.
It is known that β-adrenoceptor antagonists are effective in the treatment of akathisia, one of the extrapyramidal side effects that occur during neuroleptic treatment. Neuroleptic-induced catalepsy, a model of neuroleptic-induced extrapyramidal side effects, was considered suitable as a model for predicting neuroleptic-induced akathisia in humans, although neuroleptic-induced catalepsy was not considered a specific test for neuroleptic-induced akathisia. Therefore, the effects of carteolol, a β-adrenoceptor antagonist, on haloperidol-induced catalepsy in rats were behaviorally studied and compared with those of propranolol and biperiden, a muscarinic receptor antagonist. Carteolol, as well as propranolol and biperiden, inhibited the haloperidol-induced catalepsy. The inhibitory effect of carteolol was almost comparable to that of propranolol, but was weaker than that of biperiden. Carteolol did not evoke postsynaptic dopamine receptor-stimulating behavioral signs such as stereotypy and hyperlocomotion in rats. Carteolol did not antagonize the inhibitory effects of haloperidol on apomorphine-induced stereotypy and locomotor activity in rats. In addition, carteolol did not evoke 5-HT1A receptor-stimulating behavioral signs such as flat body posture and forepaw treading and did not inhibit 5-hydroxytryptophan-induced head twitch in rats. Finally, carteolol did not inhibit physostigmine-induced lethality in rats. These results strongly suggest that carteolol improves haloperidol-induced catalepsy via its β-adrenoceptor antagonistic activity and is expected to be effective in the treatment of akathisia without attenuating neuroleptic-induced antipsychotic effects due to its postsynaptic dopamine receptor antagonistic activity. Received: 7 March 1996/ Final version: 27 November 1996  相似文献   
992.
Chronic compression (10 mm Hg for 1 week) of spinal nerve roots in a dog experimental model has been shown to reduce nerve conduction velocity. Although injured, the compressed nerve roots demonstrated increased resistance to acute compression applied in addition to the chronic compression after 1 week. In the present study reduction of nerve conduction velocity induced by chronic compression recovered when the duration of compression was extended to 1 month. However, the tolerance to additionally applied compression was still present. This study provides important base-line data for continued studies of the basic mechanisms of the development of tolerance to changes in compression pressure levels in chronically compressed nerve roots.  相似文献   
993.
Hepatocyte growth factor (HGF)/scatter factor (SF) is a cytokine which is produced by mesenchymal cells and stimulates the motility of some epithelial cells, including cancer cells and vascular endothelial cells. Two human lung cancer cell lines, PC-1 and PC-13, were found to produce a protein which was indistinguishable from HGF/SF with regard to biological activities and immunological characteristics, although they were derived from epithelial cells. In general, highly aggressive cancer cells often show some mesenchymal characteristics, and production of HGF/SF by cancer cells is also considered as a phenomenon of acquisition of mesenchymal phenotype, which may be involved in cancer invasion and progression. These cell lines showed no apparent response to exogenous HGF/SF. In addition, no c-met proto-oncogene product was detectable in these cells by Western blot analysis. Although the function of HGF/SF produced by cancer cells, either autocrine or paracrine stimulation, remains to be studied, this is the first report to describe cancer cells producing HGF/SF.  相似文献   
994.
We have previously purified smg GDP dissociation stimulator (GDS) from bovine brain and isolated its cDNA from a bovine brain cDNA library. smg GDS stimulates the GDP/GTP exchange reaction of a group of small GTP-binding proteins (G proteins), including at least c-Ki-ras p21, smg p21A, smg p21B, rhoA p21 and rhoB p21, by stimulating the dissociation of GDP from and the subsequent binding of GTP to each small G protein. In this study, we have isolated and sequenced the cDNA of smg GDS from a human brain cDNA library using the cloned bovine smg GDS cDNA. The cDNA has an open reading frame encoding a protein of 558 amino acids with a calculated Mr value of 61,122. Human smg GDS shares 93% nucleotide and 96% amino acid sequence homologies with bovine smg GDS. The isolated cDNA is expressed in Escherichia coli, and the encoded protein shows the physical and functional properties similar to those of bovine smg GDS.  相似文献   
995.
Hepatocyte growth factor (HGF)/scatter factor (SF) is a cytokine which is produced by mesenchymal cells and stimulates the motility of some epithelial cells, including cancer cells and vascular endothelial cells. Two human lung cancer cell lines, PC-1 and PC-13, were found to produce a protein which was indistinguishable from HGF/SF with regard to biological activities and immunological characteristics, although they were derived from epithelial cells. In general, highly aggressive cancer cells often show some mesenchymal characteristics, and production of HGF/SF by cancer cells is also considered as a phenomenon of acquisition of mesenchymal phenotype, which may be involved in cancer invasion and progression. These cell lines showed no apparent response to exogenous HGF/SF. In addition, no c-met proto-oncogene product was detectable in these cells by Western blot analysis. Although the function of HGF/SF produced by cancer cells, either autocrine or paracrine stimulation, remains to be studied, this is the first report to describe cancer cells producing HGF/SF.  相似文献   
996.
997.
998.
The authors present a modified surgical procedure for extracranial vertebral artery reconstruction. The use of the proposed technique results in access to the V3 segment of the vertebral artery between the C-1 and C-2 vertebrae through the retrojugular space without requiring bone rongeuring. A saphenous vein bypass graft was placed between the common carotid artery and the V3 segment of the vertebral artery in three patients with bilateral occlusive lesions of the proximal vertebral arteries.  相似文献   
999.
Histological analyses of 16 autopsies of pancreatic carcinoma [9 cases after intra-arterial infusion chemotherapy (IAC), and 7 cases of systemic chemotherapy (SC)] were performed. Histological effects of chemotherapy (Shimosato) were seen in 15 cases, but less than 5 Grade II a. cases of IAC and 4 cases of SC showed Grade IIa, 3 cases of IAC and 3 cases of SC showed Grade I. The ratio of Grade IIa was almost the same in IAC and SC. But histologically, anaplastic change, sarcomatous change and Bizarre cells, immunohistologically positive to anti-EMA and Vimentin antibody, were dominant in IAC. And clinically, serum tumor markers (CEA, CA19-9) were fewer in almost all the cases in IAC. These results may suggest that the anti-tumor effect of IAC was greater than the histological appearance.  相似文献   
1000.
Thirty-seven patients with tracheobronchial lesions by malignant tumor were treated with Nd-YAG laser. Thirty-seven patients were twenty-three males and fourteen females and ages ranged from 34 to 79 years. Diseases included were primary tracheal tumor in 3 cases, lung cancer in 16 (8 squamous cell carcinoma, 5 adenocarcinoma, 2 large cell carcinoma, 1 small cell carcinoma), cancer of adjacent organs in 9 (5 thyroid cancers, 4 esophageal cancers), and metastatic cancer to the lung or mediastinal lymph nodes in 9 (4 renal cell carcinoma, 2 thyroid cancer, one patient respectively, colon cancer and breast cancer). Intermittent irradiation of YAG laser was done for 0.5 second at 30-40 Watt through flexible bronchoscope under local anesthesia. It was repeated 1 to 41 times (mean 4.1 times) and energy amount was 148 Joules to 18,513 Joules (mean 3,305 J). The result was; stenosis disappeared in 22 cases (59.4%), improved in 14 (37.8%), and in one case YAG laser therapy discontinued due to intractable bleeding. The Nd-YAG laser therapy for tracheobronchial lesions by malignant tumor is very useful to improve dyspnea or atelectasis.  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