全文获取类型
收费全文 | 82579篇 |
免费 | 6850篇 |
国内免费 | 1946篇 |
专业分类
耳鼻咽喉 | 953篇 |
儿科学 | 2410篇 |
妇产科学 | 2111篇 |
基础医学 | 10911篇 |
口腔科学 | 1534篇 |
临床医学 | 10653篇 |
内科学 | 15358篇 |
皮肤病学 | 1704篇 |
神经病学 | 6716篇 |
特种医学 | 2271篇 |
外国民族医学 | 17篇 |
外科学 | 7713篇 |
综合类 | 4684篇 |
现状与发展 | 4篇 |
一般理论 | 69篇 |
预防医学 | 8080篇 |
眼科学 | 1465篇 |
药学 | 6271篇 |
25篇 | |
中国医学 | 1705篇 |
肿瘤学 | 6721篇 |
出版年
2024年 | 143篇 |
2023年 | 907篇 |
2022年 | 1724篇 |
2021年 | 2783篇 |
2020年 | 2049篇 |
2019年 | 2559篇 |
2018年 | 2811篇 |
2017年 | 2293篇 |
2016年 | 2372篇 |
2015年 | 2942篇 |
2014年 | 3678篇 |
2013年 | 4505篇 |
2012年 | 6311篇 |
2011年 | 6569篇 |
2010年 | 3857篇 |
2009年 | 3161篇 |
2008年 | 4976篇 |
2007年 | 4966篇 |
2006年 | 4940篇 |
2005年 | 4719篇 |
2004年 | 4136篇 |
2003年 | 3842篇 |
2002年 | 3408篇 |
2001年 | 1260篇 |
2000年 | 1082篇 |
1999年 | 1058篇 |
1998年 | 980篇 |
1997年 | 804篇 |
1996年 | 681篇 |
1995年 | 644篇 |
1994年 | 542篇 |
1993年 | 462篇 |
1992年 | 511篇 |
1991年 | 442篇 |
1990年 | 361篇 |
1989年 | 282篇 |
1988年 | 315篇 |
1987年 | 245篇 |
1986年 | 216篇 |
1985年 | 214篇 |
1984年 | 184篇 |
1983年 | 144篇 |
1982年 | 152篇 |
1981年 | 158篇 |
1980年 | 124篇 |
1979年 | 94篇 |
1978年 | 90篇 |
1977年 | 68篇 |
1976年 | 62篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
Cynthia S. Pomerleau Anne W. Garcia Ovide F. Pomerleau Oliver G. Cameron 《Psychoneuroendocrinology》1992,17(6):627-638
Nicotine intake, menstrual and smoking withdrawal symptomatology, and baseline cortisol and MHPG were assessed in nine women smokers under conditions of ad lib smoking and overnight abstinence in three menstrual phases (early follicular, mid-to-late follicular, and late luteal). A trend towards higher nicotine intake p <0.100 was observed in the mid-to-late follicular phase. Although me menstrual symptomatology was not significantly elevated during the smoking abstinence condition overall, abstinence appeared to prevent the normal reduction in symptomatology during the mid-to-late follicular phase that occurred under conditions of ad lib smoking. Menstrual and withdrawal symptoms were highly correlated, and both were most pronounced during the late luteal/abstinence condition. The smoking-specific item “craving” reflected this pattern, though in attenuated form, suggesting that the observed exacerbation of withdrawal symptomatology was not simply due to generalized dysphoria, as queried in both instruments. MHPG was significantly elevated in the late luteal phase, whereas cortisol was significantly higher during ad lib smoking than during abstinence and tended to be highest in the mid-to-late follicular phase. Further investigation will be needed to determine the functional significance of these findings for understanding and treating smoking in women. 相似文献
92.
R. Ehrlich R. J. Wenning G. W. Johnson S. H. Su D. J. Paustenbach 《Archives of environmental contamination and toxicology》1994,27(4):486-500
The identity and relative contributions of various sources of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) to recently deposited sediments collected in Newark Bay and its major tributaries were determined using polytopic vector analysis (PVA), a multivariate statistical technique relatively new in the chemometric literature. The concentrations of 2,3,7,8-substituted PCDD/Fs were assayed in eighty-one surface and near-surface sediment samples collected from the Passaic River, Hackensack River, Arthur Kill, Elizabeth River, Kill Van Kull, Port Elizabeth, and Port Newark navigation channels and Robins Reef, which is located in New York Harbor. PVA modeling revealed five predominant 2,3,7,8-substituted PCDD/F fingerprint patterns in geographically plausible distributions throughout the estuary. This was consistent with the current understanding of hydrodynamic and sedimentation conditions reported in the literature for Newark Bay. Three patterns contained 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), which is alleged to originate from a single industrial source on the lower Passaic River. One of the fingerprints containing 2,3,7,8-TCDD was present in moderate proportions (10–20%) in surface sediments near the site, but was generally observed in low abundance (<5%) elsewhere in the estuary. A fingerprint pattern characteristic of PCDD/F profiles in effluents from municipal sewage and waste water treatment plants was widely distributed in the estuary, but reached its highest relative proportions in the Elizabeth River. A third fingerprint pattern was highest in the Arthur Kill and lower Passaic River and closely matched the residue patterns found in several types of combustion sources. A fourth finger-print pattern in Hackensack River and lower Passaic River sediment matched the PCDD/F profile reported in PCB Aroclor® formulations. A fifth fingerprint pattern matched the profile in recycled pulp and paper mill effluents and was highest in Kill van Kull and upper Passaic River sediment. The majority of PCDD/Fs in sediment from Reaches B, C, and D of Port Newark and Port Elizabeth were attributable to sediments transported via the Arthur Kill and the Kill Van Kull. These results are consistent with those previously reported using principal components analysis, which indicated that 2,3,7,8-substituted PCDD/F patterns in the sediments of Newark Bay are consistent with discharges from multiple sources. 相似文献
93.
R L Chen I J Su K H Lin S H Lee D T Lin W M Chuu K S Lin L M Huang C Y Lee 《American journal of clinical pathology》1991,96(2):171-176
Ten cases of pediatric fulminant hemophagocytic syndrome, encountered between 1986 and 1989, are described. They occurred in the summer, and the patients presented with fever, jaundice, hepatosplenomegaly, pancytopenia, coagulopathy, and abnormal liver function. Bone marrow studies revealed infiltration by atypical T-lymphoid cells, rare B immunoblasts, and mature histiocytes with hemophagocytosis. Initially, histiocytic medullary reticulosis was suspected in six cases. The clinical course was characterized by rapid deterioration, with a mean period of 16 days from onset of fever to death. The main causes of death were coagulopathy with multiple organ failure and opportunistic infection. In seven of eight cases studied by serologic assay and Southern blot hybridization, acute or active Epstein-Barr virus (EBV) infection was documented. It is suggested that an atypical or fulminant form of primary EBV infection distinct from classic infectious mononucleosis was prevalent in previously healthy children in Taiwan. Younger age involvement and seasonal clustering were characteristic of the disorder described. 相似文献
94.
人体中氧氟沙星的立体选择性代谢 总被引:2,自引:1,他引:1
5名健康志愿者日服单剂300mg氧氟沙星[(±)-Of1]后,采用立体选择性的RP-HPLC手性流动相添加剂法测定尿中S-(-)-Of1和R-(+)-Of1浓度结果显示Of1在人体内呈现立体选择性代谢。尿中排泄的S-(-)-Of1/R-(+)-Of1之比随时间变化。服药后2hS/R是0.875,24h增加到1.150.S-(-)-Of1的消除半衰期(t1/2)是4.57h;消除速率常数(k)是0.154h;药时曲线下的面积(AUC)为1.17mg·h-1.mL-1;R-(+)-Of1的t1/2为4.18h,k为0.168h-1,AUC是1.78mg·h-1·mL-1;经配对t检验这三对参数间有显著性差异,P值分别小于0.01,0.001和0.005.因此两对映体在人体内呈现立体选择性处置 相似文献
95.
96.
97.
98.
99.
CLOTBUST: Design of a Randomized Trial of Ultrasound-Enhanced Thrombolysis for Acute Ischemic Stroke 总被引:4,自引:0,他引:4
Andrei V. Alexandrov MD Anne W. Wojner PhD James C. Grotta MD 《Journal of neuroimaging》2004,14(2):108-112
BACKGROUND: Intravenous tissue plasminogen activator (TPA) therapy can be monitored with 2 MHz transcranial Doppler (TCD). This article describes the design of CLOTBUST (combined lysis of thrombus in brain ischemia using transcranial ultrasound and systemic TPA), the first prospective international multicenter randomized clinical trial of noninvasive externally applied ultrasound to enhance systemic thrombolysis in human stroke. SUBJECTS: Patients with acute ischemic stroke eligible for intravenous TPA therapy within 3 hours of symptom onset who have detectable middle cerebral artery occlusion on a prebolus TCD are included in this trial. All patients receive standard 0.9 mg/kg TPA therapy. Patients are randomized (1:1) to either 2 hours of continuous monitoring with TCD or placebo monitoring. FDA-approved portable diagnostic TCD equipment and standard headframes (Marc series, Spencer Technologies, Seattle, WA) are used. Output of TCD units is set at 100% power achievable at depths of insonation that display the worst TIBI flow grade signals. METHODS AND END-POINTS: Acute MCA occlusion on prebolus TCD is defined as thrombolysis in brain ischemia (TIBI) flow grades 0-3. Treating physicians are blinded to randomization assignment, and certified scorers measure stroke severity using the National Institute of Health Stroke Scale (NIHSS). Safety of continuous TCD monitoring is determined by rates of symptomatic (NIHSS score increase by 4+ points) intracerebral hemorrhage within 72 hours after initial symptom onset. Potential enhancement of TPA therapy will be determined using combined primary end-point of early complete recanalization on TCD (TIBI flow grades 4-5), dramatic recovery (NIHSS < or = 3 points), or decline in the NIHSS > or = 10 points repeatedly measured every 30 minutes within 2 hours after TPA bolus. Other end-points include recovery at 24 hours and 3 months, modified Rankin scores (mRS) are obtained at 90 days, and favorable outcome is determined as NIHSS or mRS scores 0-1. CONCLUSIONS: The aim of phase II CLOTBUST trial is to determine the rates of early complete recanalization and dramatic/early clinical recovery in TPA + TCD and TPA groups. The sample size is set at 126 patients since a medium effect size (.50) is anticipated for TPA + TCD group vs TPA alone to achieve combined primary end-point. 相似文献
100.