全文获取类型
收费全文 | 18721篇 |
免费 | 1238篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 216篇 |
儿科学 | 419篇 |
妇产科学 | 345篇 |
基础医学 | 2583篇 |
口腔科学 | 319篇 |
临床医学 | 1618篇 |
内科学 | 4826篇 |
皮肤病学 | 410篇 |
神经病学 | 1618篇 |
特种医学 | 613篇 |
外科学 | 2653篇 |
综合类 | 238篇 |
一般理论 | 8篇 |
预防医学 | 1394篇 |
眼科学 | 412篇 |
药学 | 1113篇 |
中国医学 | 77篇 |
肿瘤学 | 1172篇 |
出版年
2023年 | 132篇 |
2022年 | 330篇 |
2021年 | 545篇 |
2020年 | 306篇 |
2019年 | 447篇 |
2018年 | 515篇 |
2017年 | 342篇 |
2016年 | 364篇 |
2015年 | 449篇 |
2014年 | 619篇 |
2013年 | 838篇 |
2012年 | 1331篇 |
2011年 | 1347篇 |
2010年 | 773篇 |
2009年 | 664篇 |
2008年 | 1125篇 |
2007年 | 1194篇 |
2006年 | 1175篇 |
2005年 | 1105篇 |
2004年 | 1007篇 |
2003年 | 959篇 |
2002年 | 952篇 |
2001年 | 132篇 |
2000年 | 117篇 |
1999年 | 160篇 |
1998年 | 198篇 |
1997年 | 164篇 |
1996年 | 164篇 |
1995年 | 120篇 |
1994年 | 115篇 |
1993年 | 98篇 |
1992年 | 100篇 |
1991年 | 99篇 |
1990年 | 88篇 |
1989年 | 69篇 |
1988年 | 79篇 |
1987年 | 83篇 |
1986年 | 66篇 |
1985年 | 87篇 |
1984年 | 97篇 |
1983年 | 92篇 |
1982年 | 110篇 |
1981年 | 123篇 |
1980年 | 107篇 |
1979年 | 64篇 |
1978年 | 74篇 |
1977年 | 87篇 |
1976年 | 61篇 |
1974年 | 52篇 |
1973年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Carol A Mathews Caroline M Nievergelt Amin Azzam Helena Garrido Denise A Chavira Jennifer Wessel Monica Bagnarello Victor I Reus Nicholas J Schork 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2007,(2):174-182
To date, only one complete genome screen for obsessive-compulsive disorder (OCD) has been published. That study identified a region of suggestive linkage (maximum lod score of 2.25) with a relatively small sample size (N = 56; 27 with OCD). Additional complete genome screens are needed to confirm this finding and identify other regions of linkage. We present the clinical characteristics and power to detect linkage of 11 multigenerational families with OCD and hoarding (N = 92; 44 with OCD), as well as heritability estimates for several quantitative traits. Families with at least two individuals with OCD were identified through probands with childhood-onset OCD. Expected lod scores were calculated for simulated genetic marker data under an additive and two dominant models assuming a dense SNP marker map. All affected individuals had an early age of onset (18 or younger). Hoarding was present in 46% of subjects. Obsessive-compulsive symptoms and hoarding were highly heritable. The maximum mean expected lod score was 3.31 for OCD and 1.39 for hoarding. We found reasonable power to detect regions of interest (lod = 2) for OCD in these families, but will need to expand our family collection to have adequate power to detect regions of interest for hoarding. 相似文献
52.
BACKGROUND: Rates of remission and relapse were studied over more than 2 years in a sample of Spanish outpatients with DSM-III-R criteria of unipolar major depressive episodes. METHODS: Patients were treated following standardised pharmacological protocols at our centre. In the first visit, the structured clinical interview for DSM-III-R (SCID) was used. The following visits were held monthly. Phases of evolution were recorded using the Hamilton Depression Rating Scale (HDRS), applying the Frank criteria. RESULTS: A significantly greater proportion of relapse was observed in the partial remission group compared to the complete remission one. The rate of relapses for patients in complete remission was 15.18%, while for patients in partial remission was 67.61%. Partial remission was significantly associated with relapses. LIMITATIONS: The short duration of the study and the decreasing sample size during the follow-up. CONCLUSIONS: Partial remission after a depressive episode seems to be strongly associated with relapses. Moreover, this clinical factor could by itself fully predict short-term relapses. CLINICAL RELEVANCE: The study shows the importance of reaching complete remission to decrease the rate of short-term relapses. 相似文献
53.
Zhang J Herman EH Knapton A Chadwick DP Whitehurst VE Koerner JE Papoian T Ferrans VJ Sistare FD 《Toxicologic pathology》2002,30(1):28-40
The characteristics and pathogenesis of the cardiovascular toxicity induced by the type III selective phosphodiesterase inhibitor SK&F 95654 were examined in 2 studies. Sprague-Dawley rats received either a single sc injection of 50, 100, or 200 mg/kg SK&F 95654 and were euthanized at 24 hours after administration of the drug (Study 1), or were given a single subcutaneous (sc) injection of 100 mg/kg SK&F 95654 and euthanized at 1, 2, 4, 6, 8,12, 24 hours, or 2 weeks after treatment (Study 2). Control rats received either DMSO or saline. Myocardial lesions and vascular lesions of the mesentery, spleen, and pancreas were seen 24 hours after dosing with either 50,100, or 200 mg/kg SK&F 95654. The frequency and severity of these lesions (evaluated after the 100 mg/kg dose) increased with time over a period of 1 to 24 hours. By 2 weeks, the lesions subsided. Cardiac lesions consisted of myocyte necrosis with hypercontraction bands, inflammatory cell infiltration, interstitial hemorrhage, and interstitial edema. Vascular lesions of the mesentery were most prominent and consisted of vasodilatation and inflammation in the small-sized vessels, arterial medial necrosis and hemorrhage, and venous thrombosis. The vascular lesions included: leukocyte adhesion to endothelial cells, transendothelial migration of leukocytes, and inflammatory cell infiltration into vessel walls. Affected vessels included arteries, terminal arterioles, capillaries, postcapillary venules, and veins. Apoptosis of endothelial and smooth muscle cells was detected in the mesenteric vasculature by both TUNEL assay and electron microscopy. Evidence of endothelial cell activation in the mesenteric arteries and veins was also observed by electron microscopy. Immunohistochemical staining detected enhanced endothelial cell expression of intercellular adhesion molecule- 1 (ICAM- 1) and von Willebrand factor (vWF) in the mesenteric arteries and veins. Mast cells were noted to be more prevalent in affected mesenteric tissue from drug-treated animals. The present findings suggest that apoptosis of endothelial and smooth muscle cells, activation of endothelial cells, recruitment of mast cells, and increased expression of adhesion molecules are important factors to the overall pathogenesis of SK&F 95654-induced vasculitis. 相似文献
54.
55.
56.
Nina L. Golitsina Andrey A. Bobkov Irina V. Dedova Dmitrii A. Pavlov Olga P. Nikolaeva Victor N. Orlov Dmitrii I. Levitsky 《Journal of muscle research and cell motility》1996,17(4):475-485
Summary The effects of various modifications of rabbit skeletal myosin subfragment 1 on thermal denaturation of subfragment 1 in ternary complexes with Mg-ADP and orthovanadate (Vi) or beryllium fluoride (BeFx) have been studied by differential scanning calorimetry. It has been shown that specific modifications of SH1 group of Cys-707 by different sulfhydryl reagents, trinitrophenylation of Lys-83, and reductive methylation of lysine residues promote the decomposition of the S1·ADP·Vi complex and change the character of structural transitions of the subfragment 1 molecule induced by the formation of this complex, but they have much less or no influence on subfragment 1 thermal stability in the S1·ADP·BeFx complex. Thus, the differential scanning calorimetric studies on modified subfragment 1 preparations reveal a significant difference between S1·ADP·Vi and S1·ADP·BeFx complexes. It is suggested that S1·ADP·Vi and S1·ADP·BeFx complexes represent structural analogues of different transition states of the ATPase cycle, namely the intermediate states S1**·ADP·Pi and S1*·ATP, respectively. It is also proposed that during formation of the S1·ADP·Vi complex the region containing both Cys-707 and Lys-83 plays an important role in the spread of conformational changes from the active site of subfragment 1 ATPase throughout the structure of the entire subfragment 1 molecule. In such a case, the effects of reductive methylation of lysine residues on the subfragment 1 structure in the S1·ADP·Vi complex are related to the modification of Lys-83. 相似文献
57.
Initial validation of the SLEEP-50 questionnaire 总被引:1,自引:0,他引:1
Initial psychometric properties of the SLEEP-50 questionnaire, designed to detect sleep disorders as listed in the Diagnostic and Statistical Manual of Mental Disorders (4th ed., Text Revision), were examined. The sample consisted of 377 college students, 246 sleep patients, 32 nightmare sufferers, and 44 healthy volunteers. The internal consistency was high (Cronbach's alpha = .85); test-retest correlations fell between .65 and .89. Principal component analysis with a direct oblimin rotation revealed a factor structure that closely matched the designed structure. Sensitivity and specificity scores were promising for all sleep disorders; the agreement between all clinical diagnoses and SLEEP-50-classifications was substantial (kappa = .77). These initial findings indicate that the SLEEP-50 seems able to detect a variety of sleep disorders. The SLEEP-50 can aid in screening for common sleep disorders in the general population. 相似文献
58.
Pituitary morphologic changes in patients with Erdheim-Chester disease have not been described in detail. We report here the
histologic and immunohistochemical findings in the autopsy obtained pituitary of a 35-yr-old woman with extensively disseminated
Erdheim-Chester disease. The posterior lobe was completely replaced by xanthogranulomatous infiltrates, providing an explanation
for the patient’s diabetes insipidus. The anterior lobe was intact and immunohistochemistry demonstrated expression of GH,
TSH, FSH, LH, and alpha subunit within the normal range. A clinically observed decrease of anterior pituitary function was
interpreted as hypothalamic in origin due to massive destruction of the hypophysial stalk and compression of the hypothalamus.
Prolactin immunoreactive cells were numerous, consistent with the view that prolactin cell hyperplasia resulted from the loss
of hypothalamic dopaminergic inhibition. Massive Crooke’s hyalinization in the ACTH-producing cells was considered unrelated
to Erdheim-Chester disease and was the consequence of treatment with pharmacologic doses of glucocorticoid hormones. It can
be concluded that prolactin cell hyperplasia may be the only finding in the adenohypophysis of patients with disseminated
Erdheim-Chester disease. It appears that in our patient the clinically apparent anterior hypopituitarism was not due to the
lack of storage but rather to insufficient release of adenohypophysial hormones caused by the defect in hypothalamic regulation. 相似文献
59.
Moore VA Varela AS Yabsley MJ Davidson WR Little SE 《Journal of clinical microbiology》2003,41(1):424-427
To determine if white-tailed deer may serve as a reservoir host for Borrelia lonestari, we used a nested PCR for the Borrelia flagellin gene to evaluate blood samples collected from deer from eight southeastern states. Seven of 80 deer (8.7%) from 5 of 17 sites (29.4%) had sequence-confirmed evidence of a B. lonestari flagellin gene by PCR, indicating that deer are infected with B. lonestari or another closely related Borrelia species. Our findings expand the known geographic range of B. lonestari and provide the first evidence of this organism in a vertebrate other than humans. 相似文献
60.
Victor A. Sorokin Vladimir F. Fedorov Victor S. Leontiev Yuri P. Blagoi Vladimir L. Galkin 《Macromolecular chemistry and physics.》1987,188(10):2301-2309
The helix-coil transition in Phage T2 DNA in the presence of 6,4 · 10?3 mol/l Mn2+ is studied using light scattering and UV spectroscopy. The transition range is about 0,5°C. Near the temperature of the end of melting Tf the molecular weight Mw and the radius of gyration Rz of the complex are observed to decrease to about one half. At a temperature 0,1–0,25°C higher than Tf, Mw and Rz pass through a minimum, which implies that aggregation is preceded by unwinding of DNA strands. Thus, rise in temperature rather than Mn2+ -induced aggregation causes DNA + Mn2+ melting. 相似文献