全文获取类型
收费全文 | 8032篇 |
免费 | 678篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 86篇 |
儿科学 | 156篇 |
妇产科学 | 155篇 |
基础医学 | 1105篇 |
口腔科学 | 107篇 |
临床医学 | 998篇 |
内科学 | 1435篇 |
皮肤病学 | 175篇 |
神经病学 | 696篇 |
特种医学 | 283篇 |
外科学 | 1215篇 |
综合类 | 87篇 |
一般理论 | 3篇 |
预防医学 | 732篇 |
眼科学 | 276篇 |
药学 | 544篇 |
中国医学 | 9篇 |
肿瘤学 | 661篇 |
出版年
2023年 | 68篇 |
2022年 | 111篇 |
2021年 | 352篇 |
2020年 | 199篇 |
2019年 | 285篇 |
2018年 | 312篇 |
2017年 | 228篇 |
2016年 | 198篇 |
2015年 | 287篇 |
2014年 | 315篇 |
2013年 | 427篇 |
2012年 | 571篇 |
2011年 | 578篇 |
2010年 | 282篇 |
2009年 | 201篇 |
2008年 | 374篇 |
2007年 | 368篇 |
2006年 | 381篇 |
2005年 | 291篇 |
2004年 | 296篇 |
2003年 | 277篇 |
2002年 | 224篇 |
2001年 | 143篇 |
2000年 | 133篇 |
1999年 | 153篇 |
1998年 | 68篇 |
1997年 | 55篇 |
1996年 | 68篇 |
1995年 | 61篇 |
1994年 | 33篇 |
1993年 | 42篇 |
1992年 | 98篇 |
1991年 | 92篇 |
1990年 | 84篇 |
1989年 | 96篇 |
1988年 | 86篇 |
1987年 | 86篇 |
1986年 | 79篇 |
1985年 | 91篇 |
1984年 | 65篇 |
1983年 | 44篇 |
1979年 | 42篇 |
1978年 | 29篇 |
1977年 | 27篇 |
1974年 | 30篇 |
1973年 | 31篇 |
1972年 | 43篇 |
1971年 | 30篇 |
1970年 | 27篇 |
1968年 | 39篇 |
排序方式: 共有8723条查询结果,搜索用时 0 毫秒
21.
B G Campling A C Haworth H M Baker D L Greer J J Holden E C Bradley J Pym D F Dexter 《Cancer》1992,69(8):2064-2074
The establishment and characterization of 11 human lung cancer cell lines are described in this article. Nine of these cell lines were established over a 5-year period, from 1983 to 1988, from patients treated at the Kingston Regional Cancer Centre. These include eight definite or probable small cell lung cancer (SCLC) lines and one adenocarcinoma line. In addition, two other SCLC cell lines were characterized. All of the lines have been in continuous culture for more than 2 years. The clinical histories of the patients from whom the cell lines were derived are outlined here. Several features of the cell lines are presented, including the following: (1) a comparison of the histologic features of the cell lines with the original biopsy specimens; (2) the expression of various markers, including cytokeratin, carcinoembryonic antigen, calcitonin, and neuron-specific enolase; (3) activities of the enzymes l-dopa decarboxylase and the brain isoenzyme of creatine kinase; (4) growth characteristics; (5) cloning efficiency in soft agar; (6) tumorigenicity in nude mice; and (7) cytogenetic studies. These cell lines, obtained directly from patients with a spectrum of drug-sensitive and drug-resistant tumors, will be valuable in vitro models of sensitivity and resistance to chemotherapy in lung cancer. 相似文献
22.
23.
24.
The postoperative patient may present with one or more of a variety of problems amenable to management by interventional radiologic techniques, which may be curative by themselves or may, in addition, require or allow successful surgical intervention. To optimize patient care, a good working relationship between the vascular surgeon and the interventional radiologist is essential. Consideration should be given to the patient's presenting signs and symptoms, the surgical history with its alteration of anatomy, the results of available noninvasive studies, and knowledge of various therapeutic alternatives. Vascular radiologic interventions include angioplasty, thrombolytic therapy, a combination of both angioplasty and thrombolysis, and newer techniques such as percutaneous valvectomy. In this report, examples of some of the experience at Indiana University are presented. Emphasis is placed on the appropriate approach to the patient. 相似文献
25.
G R Girard W E Bondinell L M Hillegass K G Holden R G Pendleton I Uzinskas 《Journal of medicinal chemistry》1989,32(7):1566-1571
A series of 7,8-fused heterocyclic tetrahydroisoquinolines were synthesized and tested as inhibitors of rabbit adrenal phenylethanolamine-N-methyltransferase (PNMT). 6,7,8,9-Tetrahydro[1,2,3]thiadiazolo[5,4-h]isoquinoline 5 (SK&F 86607) was found to be a potent inhibitor of PNMT with an IC50 similar to that of 7,8-dichloro-1,2,3,4-tetrahydroisoquinoline (1, SK&F 64139). The isomeric tetrahydro[1,2,3]thiadiazolo[4,5-h]- and tetrahydro[1,2,5]thiadiazolo[3,4-h]isoquinolines, 13 and 20, were also potent PNMT inhibitors. However, substitution of Cl at position 5 (17) resulted in loss of potency similar to the loss observed in the 5-chloro analogue of 1. The 1,2,5 isomer 20 showed only a small drop in activity at 10(-6) M. All of the thiadiazoles were more potent than the 7,8-benzo-fused analogue 36. Fusion of other five-membered heterocyclic ring systems at the 7,8-position, e.g. triazole 22 and imidazoles 24 and 26, resulted in a decrease of PNMT inhibition. The alpha-adrenoreceptor affinities of 1 and 5 were also compared. 相似文献
26.
G A Dienel N F Cruz K Mori J E Holden L Sokoloff 《Journal of cerebral blood flow and metabolism》1991,11(1):25-34
Steady-state distribution spaces of 2-[14C]deoxyglucose ([14C]DG), glucose, and 3-O-[14C]methylglucose at various concentrations of glucose in brain and plasma ranging from hypoglycemic to hyperglycemic levels have been determined by direct chemical analyses in the brains of conscious rats. The hexose concentrations were measured chemically in freeze-blown brain extracted with ethanol to avoid the degradation of acid-labile products of [14C]DG back to free [14C]DG that has been found to occur with the more commonly used perchloric acid extraction of brain. Corrections were also made for nonphosphorylatable, labeled products of [14C]DG found in the nonacidic fractions of the brain extracts, which were previously included with the assayed [14C]DG, and for the contribution of the hexose contents in the blood in the brain, which was found to be particularly critical for the determination of the glucose distribution space, especially in hypoglycemic states. From the measured contents of the hexoses in brain and plasma, the relationships of the tissue concentrations and distribution spaces of each of the hexoses and of the lambda (i.e., ratio of tissue distribution space of DG to that of glucose) of the DG method to the tissue glucose concentration were derived. The lambda was then quantitatively related to the measured equilibrium ratio for [14C]methylglucose over the full range of brain and plasma glucose levels. By combining these new data with the values for the lumped constant, the factor that converts the rate of DG phosphorylation to glucose phosphorylation, previously determined in rats over the same range of plasma glucose levels, the phosphorylation coefficient was calculated and the lumped constant graphed as a function of the measured distribution space in brain for [14C]methylglucose. 相似文献
27.
Single photon emission computed tomography using 99mTc-HM-PAO in the routine evaluation of Alzheimer's disease 总被引:1,自引:0,他引:1
T A Hurwitz W Ammann D Chu C Clark J Holden R Brownstone 《The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques》1991,18(1):59-62
Regional cerebral blood flow was studied in 7 patients with clinically suspected Alzheimer's disease and 10 normal controls by single photon computed emission tomography (SPECT) using HM-PAO. All patients with Alzheimer's disease and no controls had parietal lobe hypoperfusion which was usually bilateral. In patients with more severe dementia hypoperfusion extended into the frontal lobes. Parietal lobe hypoperfusion corresponds to parietal lobe degeneration which is the one of the first neocortical regions to show the typical degenerative changes of Alzheimer's disease. SPECT with HM-PAO is a non-invasive investigation available in most nuclear medicine departments and complements existing tests in the routine evaluation of patients presenting with dementia. 相似文献
28.
M D Holden 《Postgraduate medicine》1992,91(8):191-4, 199-200
29.
30.