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   32059篇
  免费   1916篇
  国内免费   63篇
耳鼻咽喉   480篇
儿科学   829篇
妇产科学   560篇
基础医学   4463篇
口腔科学   716篇
临床医学   3310篇
内科学   6024篇
皮肤病学   447篇
神经病学   3149篇
特种医学   1331篇
外国民族医学   12篇
外科学   4503篇
综合类   309篇
一般理论   18篇
预防医学   2863篇
眼科学   953篇
药学   2282篇
中国医学   54篇
肿瘤学   1735篇
  2022年   242篇
  2021年   511篇
  2020年   339篇
  2019年   471篇
  2018年   584篇
  2017年   435篇
  2016年   475篇
  2015年   599篇
  2014年   782篇
  2013年   1151篇
  2012年   1733篇
  2011年   1774篇
  2010年   1013篇
  2009年   991篇
  2008年   1629篇
  2007年   1729篇
  2006年   1679篇
  2005年   1678篇
  2004年   1633篇
  2003年   1427篇
  2002年   1458篇
  2001年   788篇
  2000年   786篇
  1999年   715篇
  1998年   388篇
  1997年   357篇
  1996年   283篇
  1995年   232篇
  1994年   208篇
  1993年   183篇
  1992年   447篇
  1991年   452篇
  1990年   438篇
  1989年   399篇
  1988年   406篇
  1987年   363篇
  1986年   362篇
  1985年   326篇
  1984年   261篇
  1983年   203篇
  1982年   154篇
  1981年   147篇
  1980年   146篇
  1979年   226篇
  1978年   175篇
  1977年   172篇
  1976年   159篇
  1975年   158篇
  1974年   177篇
  1972年   149篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Deregulated signal transduction via the epidermal growth factor receptor (EGF-R) family of protein-tyrosine kinase growth factor receptors is associated with proliferative diseases. We describe a class of compounds (4,5-dianilinophthalimides) that inhibit the EGF-R protein-tyrosine kinase in vitro with high selectivity. In cells, 4,5-dianilinophthalmide selectively inhibited both ligand-induced EGF-R and p185c-erbB2 autophosphorylation and c-fos mRNA induction. Antitumor activity could be demonstrated in vivo against xenografts of the A431 and SK-OV-3 tumors, which overexpress the EGF-R and p185c-erbB2, respectively. In contrast, a platelet-derived growth factor-driven tumor was not inhibited by 4,5-dianilinophthalimide, which is compatible with its cellular selectivity and hypothesized mechanism of action. No overt cumulative toxicity was observed during treatment even though high efficacy was observed, indicating a good therapeutic window. 4,5-Dianilinophthalimides may offer therapeutic agents for the treatment of hyperproliferative diseases that overexpress EGF-R family protein-tyrosine kinases or their ligands.  相似文献   
52.
The report of a lobectomy for bronchogenic carcinoma in 1912, by Hugh Morriston Davies of London, and without precedent, describes a surgical technique strikingly similar to that of today. Unfortunately, Davies' patient died because postoperative management of the pleural space was not yet well understood. The tumor had been identified by radiographic examination and the diagnosis confirmed by cytological examination of the sputum. The operative technique included individual ligation of hilar vessels and suture closure of the bronchus, neither of which was to be reported again for more than 20 years. More effective management of the pleural space was described, without special emphasis, by Harold Brunn of San Francisco 17 years later.  相似文献   
53.
54.
An abnormal fibrinogen was identified in a 10-year-old male with a mild bleeding tendency; several years later, the patient developed a thrombotic event. Fibrin polymerization of plasma from the propositus and his mother, as measured by turbidity, was impaired. Plasmin digestion of fibrinogen and thrombin bound to the clot were both normal. The structure of clots from both plasma and purified fibrinogen was characterized by permeability, scanning electron microscopy and rheological measurements. Permeability of patients' clots was abnormal, although some measurements were not reliable because the clots were not mechanically stable. Consistent with these results, the stiffness of patients' clots was decreased approximately two-fold. Electron microscopy revealed that the patients' clots were very heterogeneous in structure. DNA sequencing of the propositus and his mother revealed a new unique point mutation that gives rise to a fibrinogen molecule with a missing amino acid residue at Aalpha-Asn 80. This new mutation, which would disrupt the alpha-helical coiled-coil structure, emphasizes the importance of this part of the molecule for fibrin polymerization and clot structure. This abnormal fibrinogen has been named fibrinogen Caracas VI.  相似文献   
55.
Primary megaureter is a common cause of obstructive uropathy in children. The imaging studies and records of 75 infants and children with primary megaureter seen at Children's Hospital were reviewed. We describe our findings and illustrate the clinical presentations, diagnosis, and treatment of this entity.  相似文献   
56.
C Oursin  E Meyer 《Der Radiologe》1992,32(2):77-79
Soft tissue calcification is a well-known complication in chronic dialysis patients. These calcifications are mainly located around the large joints. Calcification of the visceral organs also occurs in these patients, even though this fact is far less known. These visceral calcifications are mostly diagnosed post mortem as they tend to be discrete and asymptomatic. In this article, we report on a chronic dialysis patient in whom extensive pulmonary calcifications occurred, leading to clinical symptoms.  相似文献   
57.
58.
H. Steve White  PhD 《Headache》2005,45(S1):S48-S56
Topiramate is a neuromodulatory compound with stabilizing properties that was initially introduced for the management of partial seizures. Topiramate has been demonstrated to modify several receptor-gated and voltage-sensitive ion channels, including voltage-activated Na+ and Ca2+ channels and non-NMDA receptors. These receptors have been implicated in the pathophysiology of both epilepsy and migraine. The pharmacological mechanisms of action for topiramate that may explain its antiepileptic and migraine preventive activities will be discussed in this review. In addition, the potential relationship between the molecular activities of topiramate and its efficacy in epilepsy and migraine prevention will be emphasized.  相似文献   
59.
Parkinson's disease is a neurodegenerative movement disorder that results from progressive loss of midbrain dopamine neurons, which consequently leads to hyperactivity of subthalamic neurons.  相似文献   
60.
The spontaneous reaction of 110 microM chlorambucil (4-[p-[bis(2-chloroethyl)amino]phenyl]-butanoic acid; CHB) with 5 mM GSH at 37 degrees C in physiological phosphate-buffered saline for 35 min gave primarily the monoglutathionyl derivative, 4-[p-[N-2-chloroethyl,N-2-S-glutathionylethyl]amino]phenyl]-butano ic acid; CHBSG) and the diglutathionyl derivative, 4-[p-[bis(2-S-glutathionylethyl]amino]phenyl]-butanoic acid (CHBSG2) with small amounts of the hydroxy-derivatives: 4-[p-[N-2-chloroethyl,N-2-hydroxy-ethyl]amino] phenyl-butanoic acid (CHBOH) and 4-[p-[N-2-S-glutathionylethyl-2-hydroxyethyl]amino]phenyl]-butanoi c acid (CHBSGOH). The inclusion of approximately physiological amounts of human glutathione S-transferases (GSTs) A1-1, A2-2, P1-1, M1a-1a M3-3 or P1-1 (for nomenclature see Mannervik et al., 1992, Biochem. J., 282, 305) had little or no catalytic effect on these reactions as determined by loss of CHB. However, GTSs A1-1 and A2-2 were associated with a significant increase of CHBSG at the expense of CHBSG2 + CHBSGOH suggesting that these GTs sequestered CHBSG at the active site. This interpretation was supported by inhibition studies which showed that CHBSG was a pure competitive inhibitor of the activity of GSTs A1-1 and A2-2 towards 1-chloro-2,4-dinitrobenzene with Ki's of 1.3 and 1.2 microM respectively. GSH transferases P1-1 and M1a-1a were inhibited by CHBSG above 10 microM. Incubation of 2 microM CHB, a concentration which may be of more significance for chemotherapy, in the presence or absence of GST A1-2 (20-50 microM) showed catalysis of GSH monoconjugation equivalent to 18% of the spontaneous rate. However, the dominant effect again was the sequestration of CHBSG which reached 74.3 +/- 1.5 (SEM)% of the total reactants at 60 min compared to 28.9 +/- 0.3(SEM)% in controls. CHBSG, although possessing a potential electrophilic centre, showed no detectable alkylation of plasmid DNA but indirect evidence was obtained that it alkylated other cellular macromolecules. It is concluded that the contribution of GSTs to catalysis of CHB detoxication will depend on factors not previously considered, namely the relative molarities of CHB, CHBSG and GSTs, and the cellular capacity to excrete CHBSG to relieve product inhibition.  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