全文获取类型
收费全文 | 55631篇 |
免费 | 4260篇 |
国内免费 | 500篇 |
专业分类
耳鼻咽喉 | 900篇 |
儿科学 | 1379篇 |
妇产科学 | 1248篇 |
基础医学 | 7758篇 |
口腔科学 | 1172篇 |
临床医学 | 5485篇 |
内科学 | 11351篇 |
皮肤病学 | 1308篇 |
神经病学 | 4407篇 |
特种医学 | 2406篇 |
外国民族医学 | 1篇 |
外科学 | 8162篇 |
综合类 | 1008篇 |
一般理论 | 28篇 |
预防医学 | 3647篇 |
眼科学 | 1475篇 |
药学 | 4072篇 |
中国医学 | 345篇 |
肿瘤学 | 4239篇 |
出版年
2023年 | 262篇 |
2022年 | 568篇 |
2021年 | 1348篇 |
2020年 | 716篇 |
2019年 | 1176篇 |
2018年 | 1425篇 |
2017年 | 1015篇 |
2016年 | 1216篇 |
2015年 | 1625篇 |
2014年 | 2108篇 |
2013年 | 2577篇 |
2012年 | 3722篇 |
2011年 | 3860篇 |
2010年 | 2301篇 |
2009年 | 1962篇 |
2008年 | 2968篇 |
2007年 | 2998篇 |
2006年 | 2791篇 |
2005年 | 2786篇 |
2004年 | 2435篇 |
2003年 | 2330篇 |
2002年 | 2126篇 |
2001年 | 1314篇 |
2000年 | 1241篇 |
1999年 | 1151篇 |
1998年 | 542篇 |
1997年 | 442篇 |
1996年 | 423篇 |
1995年 | 366篇 |
1994年 | 359篇 |
1993年 | 288篇 |
1992年 | 776篇 |
1991年 | 627篇 |
1990年 | 635篇 |
1989年 | 618篇 |
1988年 | 598篇 |
1987年 | 513篇 |
1986年 | 509篇 |
1985年 | 488篇 |
1984年 | 394篇 |
1983年 | 373篇 |
1982年 | 271篇 |
1981年 | 279篇 |
1980年 | 252篇 |
1979年 | 402篇 |
1978年 | 295篇 |
1977年 | 238篇 |
1975年 | 221篇 |
1974年 | 252篇 |
1973年 | 259篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
71.
72.
73.
Thomas L. Patterson Shirley J. Semple Lydia R. Temoshok J. Hampton Atkinson J. Allen McCutchan Kristy A. Straits-Trster James L. Chandler Igor Grant 《Journal of Applied Biobehavioral Research》1993,1(1):64-87
The significance of life stress, coping, and social support was examined in relation to depressive symptomatology in a sample of 160 asymptomatic and mildly symptomatic HIV-antibody-positive (HIV+) men. The participants (mean age = 32 years) were interviewed about the life stress that they had experienced in the previous 6 相似文献
74.
Anne T. Berg Shlomo Shinnar‡§ Eugene D. Shapiro Morton E. Salomon‡ Ellen F. Crain‡ W. Allen Hauser§ 《Epilepsia》1995,36(4):334-341
Summary We conducted a matched casecontrol study to identify risk factors for first febrile seizures, with special emphasis on characteristics of the acute illness episode. Cases were identified through hospital emergency departments; controls were identified through outpatient clinics and emergency departments. Sixtynine children with first febrile seizures and no history of previous unprovoked seizures were matched for age (±6 months), site of routine pediatric care, and date of visit (±weeks) with 1 or 2 febrile controls who had no history of previous febrile or unprovoked seizures. Medical records for the index visit were reviewed, and parents were interviewed by telephone. Illness characteristics examined included height of temperature, type of underlying illness, contact with a physician during the illness but before the index visit, and use of acetaminophen or decongestants. Family history of febrile and of unprovoked seizures, sociodemographic characteristics, daycare use, and selected preand perinatal variables were also studied. On multivariable analysis, significant independent risk factors were height of temperature, history of febrile seizures in a firstor in a higher degree relative. Gastroenteritis as the underlying illness had a significant inverse (i.e., protective) association with febrile seizures. Maternal smoking during pregnancy was a marginally significant predictor of febrile seizures. 相似文献
75.
Robert K.P Chow MD Vincent C Ho MD FRCPC 《Journal of the American Academy of Dermatology》1996,34(6):1047-1060
Critical to the proper management of pyoderma gangrenosum are correct diagnosis, identification and treatment of any underlying disorder, and the proper choice of topical and systemic therapy. Many agents are available for the treatment of pyoderma gangrenosum. We review the current therapeutic options, their efficacy and side effects, and we offer some guidelines for their proper selection. 相似文献
76.
PURPOSETo demonstrate the spectrum of CT and MR imaging findings in patients with Wegener granulomatosis and to determine how often these findings could be attributed to either direct extension from paranasal or orbital disease sites, remote granulomas, or central nervous system (CNS) vasculitis.METHODSWe retrospectively reviewed the CT or MR studies of 15 patients with Wegener granulomatosis.RESULTSAbnormal findings were seen in 7 patients (5 examined with MR imaging, 2 with CT). Findings included dural thickening and contrast enhancement (3 patients), infarcts (2 patients), regions of hyperintense signal on T2-weighted MR images (2 patients), and abnormal MR signal in the brain stem (2 patients). Three patients with imaging findings of dural enhancement and thickening were thought to have remote granulomatous lesions involving the dura. No patients had extension from sites external to the CNS or clinical findings suggestive of CNS vasculitis.CONCLUSIONThe spectrum of CT and MR findings in Wegener granulomatosis includes dural thickening and enhancements cerebral infarction, and MR signal abnormalities in the brain stem and white matter. Presumed remote granulomatous lesions were the most common causes of CNS findings in this study. Complications related to non-CNS disease (eg, hypertension, endocarditis) also appear to have played a role in some patients. 相似文献
77.
Jin Woo Kim M.D. Ho Shik Kim M.D. In Kyung Kim M.D. Mee Ran Kim M.D. Eun Young Cho B.S. Heung Kee Kim M.D. Joon Mo Lee M.D. Sung Eun Namkoong M.D. 《Gynecologic oncology》1998,69(3):230-236
Transforming growth factor-β1 (TGF-β1) is known to be a potent growth inhibitor for many cell types, including most epithelial cells. In skin keratinocytes, TGF-β1 has been shown to inhibit growth and to rapidly reduce c-mycexpression. However, the molecular mechanism of TGF-β1 action on cell growth of cervical carcinoma has not yet been elucidated. We thus assessed the effect of TGF-β1 on the growth of cervical carcinoma cell lines. Two cervical squamous carcinoma cell lines, CUMC-3 and CUMC-6, were incubated with varying concentrations of TGF-β1, and growth inhibition was evaluated with tetrazolium-based colorimetric assay. After culture in TGF-β1 for 24 h, inhibition of growth was detected in a dose-dependent manner at concentrations of 0.1–10 ng/ml in both cell lines. This effect of TGF-β1 on cultured carcinoma cells was associated with apoptotic process including oligonucleosomal ladder DNA and apoptotic body formations. Northern blot analysis revealed c-mycmRNA expression was suppressed by 10 ng/ml of TGF-β1 following 3 h of treatment in both cell lines. Western blot analysis showed that the level of p27Kip1protein was increased after TGF-β1 treatment in both cell lines. These results suggest that the mechanisms by which TGF-β1 inhibits the growth of cervical carcinoma are complex and may include effects on down-regulation of c-mycgene, and overexpression of p27Kip1protein. 相似文献
78.
79.
Purpose. To determine whether the non-toxic pentameric B subunit of Cholera toxin (CTB) binding to ganglioside GM1 on both the lipid vesicles and epithelial cells may provide a means to target lipid vesicles to mucosal cells expressing surface GM1.
Methods. Sonicated lipid vesicles containing ganglioside GM1 were prepared. Inter-vesicle cross-linking due to pentameric CTB binding to these GM1 vesicles was determined with a sub-micron particle analyzer. Association of CTB to GM1 vesicles was analyzed with continuous sucrose gradient centrifugation. CTB-mediated binding of GM1 vesicles to human mucosal epithelial cells (Caco-2 and HT-29), mucous membranes of mouse trachea, and nasal tissues were detected with fluorescent labeled vesicles.
Results. An increase in lipid particle size due to binding of CTB to lipid vesicles and inter-vesicles cross-linking was detected. At a 30-to-1 mole ratio of membrane-bound GMl-to-CTB, optimum increase in GM1 vesicle aggregation, was detected. Under such conditions, all the added CTB molecules were associated with GM1 vesicles. Time course analysis showed that inter-vesicles cross linking by CTB was detectable within 10 min. and reached a maximum value at 60 min. CTB associated GM1-vesicles bind to mucosal epithelial cells HT-29 and Caco-2 with similar affinity [Kd = 7.8 × 10–4 M lipid (Caco-2) and 7.6 × 10–4 M lipid (HT-29)]. GM1 mediated binding specificity was demonstrated by blocking with anti-GMl antibody and the insignificant degree of CTB-associated GM1 vesicle binding to GM1 deficient C6 cells.
Conclusions. The CTB-mediated GM1 binding to multiple membrane surfaces provides selective localization of GM1 vesicles to GM1 expressing mucosal cells and tissues. The strategy may be useful in localizing drugs and proteins to gut and respiratory tract mucosa. 相似文献
80.
Claus Jacob Alexander Y. Safronov Sonia Wilson H.Allen O. Hill Tim F. Booth 《Journal of electroanalytical chemistry (Lausanne, Switzerland)》1997,431(1):7-10
A novel chiral redox-active ferrocene compound (FcVI) with amphiphilic properties has been synthesized. Cryogenic Transmission Electron Microscopy (cryo-TEM) has been used to estimate the shape and size of the FcVI aggregates in solution. Uni- and multi-lamellar vesicles (between 40 and 300 nm in diameter) were observed in water. Large particles (of more than 1 μm in diameter) with a hexagonal fine structure were found in 50 mM aqueous Na2SO4 solution. Sonication transformed the latter into ‘rosette’-like structures. Cyclic voltammetry has been employed to investigate the electrochemical properties of FcVI. The amphiphile adsorbed on graphite electrodes and a reversible electrochemical behaviour, characteristic of ferrocene, was observed with redox potentials between 330 and 350 mV. 相似文献