全文获取类型
收费全文 | 2853377篇 |
免费 | 231515篇 |
国内免费 | 19724篇 |
专业分类
耳鼻咽喉 | 40088篇 |
儿科学 | 81371篇 |
妇产科学 | 74221篇 |
基础医学 | 394944篇 |
口腔科学 | 80314篇 |
临床医学 | 265265篇 |
内科学 | 556199篇 |
皮肤病学 | 56230篇 |
神经病学 | 231314篇 |
特种医学 | 112786篇 |
外国民族医学 | 1036篇 |
外科学 | 426788篇 |
综合类 | 95866篇 |
现状与发展 | 50篇 |
一般理论 | 1063篇 |
预防医学 | 216664篇 |
眼科学 | 68610篇 |
药学 | 222088篇 |
168篇 | |
中国医学 | 16463篇 |
肿瘤学 | 163088篇 |
出版年
2021年 | 28739篇 |
2019年 | 26058篇 |
2018年 | 34363篇 |
2017年 | 27305篇 |
2016年 | 28854篇 |
2015年 | 35099篇 |
2014年 | 48767篇 |
2013年 | 66527篇 |
2012年 | 91206篇 |
2011年 | 96596篇 |
2010年 | 57369篇 |
2009年 | 53335篇 |
2008年 | 86390篇 |
2007年 | 91515篇 |
2006年 | 91904篇 |
2005年 | 89806篇 |
2004年 | 83122篇 |
2003年 | 79758篇 |
2002年 | 77835篇 |
2001年 | 134469篇 |
2000年 | 139591篇 |
1999年 | 118889篇 |
1998年 | 34636篇 |
1997年 | 31737篇 |
1996年 | 30498篇 |
1995年 | 29297篇 |
1994年 | 27282篇 |
1993年 | 24851篇 |
1992年 | 92362篇 |
1991年 | 88420篇 |
1990年 | 85010篇 |
1989年 | 82234篇 |
1988年 | 75968篇 |
1987年 | 74535篇 |
1986年 | 70244篇 |
1985年 | 66665篇 |
1984年 | 49737篇 |
1983年 | 42189篇 |
1982年 | 24999篇 |
1979年 | 45717篇 |
1978年 | 31691篇 |
1977年 | 26827篇 |
1976年 | 24643篇 |
1975年 | 26110篇 |
1974年 | 32187篇 |
1973年 | 30417篇 |
1972年 | 28635篇 |
1971年 | 26516篇 |
1970年 | 24885篇 |
1969年 | 23243篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Matthew J Matasar Ellen K Ritchie Nathan Consedine Carol Magai Alfred I Neugut 《European journal of cancer prevention》2006,15(4):367-370
Despite significant improvements in the prognosis of acute promyelocytic leukemia brought about by therapeutic advances, understanding of the epidemiology of acute promyelocytic leukemia remains limited. Earlier reports have suggested that Hispanics may have an increased incidence of acute promyelocytic leukemia, but no systematic analysis of national data has yet been reported. We performed a retrospective cohort study, using data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute from 1992-2001 in order to compare leukemia incidence rates as a function of race and ethnicity. We identified 709 cases of acute promyelocytic leukemia and analyzed incidence rates by race and sex. Hispanics were not found to have greater lifetime incidence rates than whites, with an incidence relative rate (IRR) of 0.86 that of whites (P=0.17). The age distribution among Hispanics was significantly different from non-Hispanic whites, with greater incidence rates for children ages 1-19 years (IRR=1.9, P=0.02) and adult ages 20-44 years (IRR=1.6, P=0.004). Blacks had lower lifetime incidence rates than non-Hispanic whites (IRR=0.75, P=0.04), Hispanics (IRR=0.64, P=0.007), and Asians (IRR=0.67, P=0.03). Asians did not differ from non-Hispanic whites in lifetime or age-specific incidence rates. These results indicate that while US Hispanics do not have greater lifetime incidence rates of acute promyelocytic leukemia, blacks have lower incidence rates of acute promyelocytic leukemia than Hispanics, non-Hispanic whites, and Asians. 相似文献
992.
993.
C G Arruda J M Aldrighi L A Bortolotto I N Alecrin J A F Ramires 《Gynecological endocrinology》2006,22(10):557-563
BACKGROUND: Arterial hypertension and postmenopausal reduction of estrogen levels may be involved in modifications of the stiffness of large arteries. OBJECTIVES: To evaluate the pulse-wave velocity (PWV) and indirectly the arterial stiffness in hypertensive postmenopausal women submitted to hormone therapy with estradiol alone or combined with norethisterone acetate. SUBJECTS: Forty-five hypertensive postmenopausal women were double-blindly, randomly assigned to three arms of treatment: placebo (group I); estradiol 2 mg/day (group II); or estradiol 2 mg/day and norethisterone acetate 1 mg/day (group III). METHODS: Arterial stiffness was assessed from PWV measurements of the common carotid and femoral arteries (CF-PWV) and the common carotid and radial arteries (CR-PWV) obtained using the automatic Complior(R) device, taken at baseline and after 12 weeks of treatment. RESULTS: After the 12-week treatment, values of CF-PWV and CR-PWV were not significantly different (p = 0.910 and p = 0.736, respectively) among the groups. Systolic blood pressure showed a positive correlation with CF-PWV in groups II and III (p = 0.02 and p < 0.001, respectively). CONCLUSIONS: PWV and arterial stiffness in postmenopausal hypertensive women did not reduce over a 12-week treatment with estradiol alone compared with the same period of treatment with estradiol combined with norethisterone acetate. 相似文献
994.
Gábor Márk Somfai Kata Miháltz Eszter Tulassay János Rigó 《Hypertension in pregnancy》2006,25(1):11-20
OBJECTIVE: Visual symptoms are common in patients with preeclampsia, and are caused by various underlying pathological changes in the retina. Blurred vision may be one of these symptoms. We describe three cases in which the underlying retinal pathology of blurred vision was clarified using optical coherence tomography (OCT), a novel, non-invasive ophthalmic imaging technique that provides micrometer-scale resolution images of the human retina. METHODS: Three patients with preeclampsia complained of blurred vision postpartum. In all cases, ophthalmoscopy was performed at the bedside, followed by the assessment of best corrected visual acuity, slit-lamp biomicroscopy, fluorescein angiography (FLA), and OCT. In all cases, the presence of central visual defects was examined by an Amsler-grid. RESULTS: In one case, the symptoms were bilateral. In all affected eyes, the patients complained of a relative central scotoma. Ophthalmoscopy showed edema in the affected maculae, while OCT examination clarified a serous neurosensory detachment of the macula. In one case, a neurosensory detachment was also detected in the papillomacular region of a fellow eye with no symptoms. In two cases, FLA was performed, but only in one case could we detect late leakage and subretinal exudates. The serous detachments observed showed total resolution in all cases within 5 to 10 weeks, with restoration of visual acuity. CONCLUSION: In patients with preeclampsia, OCT may provide a useful method for the precise assessment of retinal changes, distinguishing retinal edema from serous neurosensory detachments. This finding may help to clarify the pathophysiological circulatory changes seen in preeclampsia. 相似文献
995.
996.
997.
998.
BACKGROUND: Diffuse peritubular capillary (PTC) C4d deposition has been shown to be associated with relatively poor graft outcome. The significance of focal PTC C4d staining in the early post-transplant period is uncertain. METHODS: Sixty-five biopsies from 53 patients with acute rejection were graded (Banff '97 criteria), stained for C4d, monocytes and T cells, and divided into three groups according to PTC C4d: (i) focal C4d (F) (14 biopsies, 14 patients), (ii) diffuse C4d (D) (23 biopsies, 15 patients) and (iii) no C4d (N) (28 biopsies, 24 patients). The three groups were compared with respect to a variety of biopsy and clinical parameters including outcome. RESULTS: The incidence of transplant glomerulitis and glomerular monocyte infiltration were significantly greater in F (64% and 2.0+/-2.0) and D (57% and 3.4+/-2.0) than in N (11% and 0.2+/-0.2). A significantly higher proportion of F (93%) demonstrated acute cellular rejection (Banff '97 grade > or = 1A) than did D (35%). The F and D groups included significantly more females (50 and 67%, respectively) than did N (21%). The percentage of patients with a second or third transplant was higher in F (29%) and D (40%) than in N (8%) (P = 0.0589). The proportion of patients with glomerular filtration rate < 30 ml/min at 12, 24 and 48 months was higher in the D and F groups than in the N, and there was a statistically significant increasing trend in odds of this outcome occurring at 48 months across the three groups (D > F > N group) (P = 0.0416). CONCLUSION: The results suggest that the biopsy findings and clinical course in patients with focal PTC C4d staining are similar to those associated with diffuse C4d. 相似文献
999.
Radiological lymphography presents drawbacks among which the risk of aggravation of the edema is most prominent. The authors report their experience with isotopic lymphography which best reproduces the physiological conditions of lymphatic drainage; it provides informations on the dermal or canalicular drainage route, the possible peripheral stasis or lymph leakage. 相似文献
1000.
Biological activity of partially purified digitalis-like substance and Na-K-ATPase inhibitor in rats
T Morise S Okamoto H Takasaki M Ikeda R Takeda F Kiuti Y Tuda 《Japanese circulation journal》1988,52(11):1309-1316
In order to study the biological activity of endogenous digitalis-like substance (DLS) and Na-K-ATPase inhibitor (ATPI), human urine was partially purified and administered to rats, and its effects on the urinary volume, urinary Na excretion and blood pressure (BP) were determined. In addition, the effect on myocardial Na-K-ATPase activity was also measured. After the extraction of 40L of urine with a reversed phase cartridge column (S-fraction), 20 ml of chloroform was added and extraction was repeated. The chloroform layer was applied to an open silica gel column, and at a fraction with ethylacetate: methanol (60: 40, T-1 fraction), DLS and ATPI were eluted at the highest concentration. The water layer was treated with charcoal (D-1 fraction). The acute administration of K-1, T-1 fraction to rats in vivo caused significant rises in urinary volume, urinary Na excretion and BP. In chronic administration of K-1 fraction, urinary Na excretion was significantly elevated and myocardial Na-K-ATPase activity was also significantly suppressed. These results suggest that DLS and ATPI cause increase in the urinary volume and urinary Na excretion and also possess a hypertensive action; and moreover, these substance may affect the heart like cardiotonic steroids and regulate BP by increasing cardiac contractility. 相似文献