全文获取类型
收费全文 | 54093篇 |
免费 | 3571篇 |
国内免费 | 165篇 |
专业分类
耳鼻咽喉 | 672篇 |
儿科学 | 1575篇 |
妇产科学 | 956篇 |
基础医学 | 6520篇 |
口腔科学 | 934篇 |
临床医学 | 5575篇 |
内科学 | 11620篇 |
皮肤病学 | 883篇 |
神经病学 | 4974篇 |
特种医学 | 2213篇 |
外国民族医学 | 1篇 |
外科学 | 9346篇 |
综合类 | 591篇 |
一般理论 | 54篇 |
预防医学 | 3580篇 |
眼科学 | 867篇 |
药学 | 3297篇 |
中国医学 | 45篇 |
肿瘤学 | 4126篇 |
出版年
2023年 | 256篇 |
2022年 | 446篇 |
2021年 | 1131篇 |
2020年 | 650篇 |
2019年 | 1146篇 |
2018年 | 1361篇 |
2017年 | 999篇 |
2016年 | 1049篇 |
2015年 | 1247篇 |
2014年 | 1919篇 |
2013年 | 2441篇 |
2012年 | 3913篇 |
2011年 | 4093篇 |
2010年 | 2309篇 |
2009年 | 1961篇 |
2008年 | 3594篇 |
2007年 | 3778篇 |
2006年 | 3723篇 |
2005年 | 3648篇 |
2004年 | 3506篇 |
2003年 | 3267篇 |
2002年 | 2996篇 |
2001年 | 536篇 |
2000年 | 421篇 |
1999年 | 569篇 |
1998年 | 610篇 |
1997年 | 496篇 |
1996年 | 393篇 |
1995年 | 396篇 |
1994年 | 372篇 |
1993年 | 321篇 |
1992年 | 340篇 |
1991年 | 308篇 |
1990年 | 293篇 |
1989年 | 278篇 |
1988年 | 270篇 |
1987年 | 243篇 |
1986年 | 238篇 |
1985年 | 226篇 |
1984年 | 262篇 |
1983年 | 242篇 |
1982年 | 250篇 |
1981年 | 209篇 |
1980年 | 152篇 |
1979年 | 131篇 |
1978年 | 123篇 |
1977年 | 109篇 |
1976年 | 77篇 |
1974年 | 90篇 |
1973年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Measles surveillance--United States, 1991. 总被引:1,自引:0,他引:1
W L Atkinson S C Hadler S B Redd W A Orenstein 《Morbidity and mortality weekly report. Surveillance summaries (Washington, D.C. : 2002)》1992,41(6):1-12
A total of 9,643 measles cases was reported from the United States in 1991, a 65.3% decrease from the 27,786 cases reported in 1990. The overall incidence of measles was 3.9 cases per 100,000 population. The highest age-specific incidence was among children < 12 months of age (46.9/100,000) and 1-4 years of age (19.6/100,000). Incidence rates among American Indians, Hispanic, and black children < 5 years of age were 19, 6, and 4 times that for non-Hispanic white children, respectively. More than 61% of all cases were reported from seven large outbreaks, which involved predominantly unvaccinated preschool-age children in large urban areas. Although reported measles cases decreased in 1991 compared with 1989-1990, only a sustained effort to provide age-appropriate vaccination will prevent another resurgence of measles. 相似文献
93.
Gregg H. Gilbert DDS Laurence G. Branch PhD Jeffrey Longmate PhD 《Journal of public health dentistry》1992,52(5):277-287
Veterans who were eligible for dental care in Department of Veterans Affairs (VA) facilities at no monetary cost responded to a mailed questionnaire. Seventy-one percent were aware that they were actually eligible for VA dental care. However, only 48 percent reported the VA as their only or primary source of dental care. Eligibility status, perceived quality of VA dental care, use of VA medical care, perception that one's income meets expenses, and perceived need for dental care were significant correlates of using the VA as one's current source of dental care. Level of formal education, perception that one's income meets expenses, transportation pattern, geographic distance from a VA facility, and eligibility status were significant correlates of using the VA as one's current medical care source. Research on VA utilization offers the opportunity to study issues of access to, and use of, a large public health care system whose patients largely receive care at no monetary cost. Veterans' use of VA dental and medical care is apparently influenced by a wide variety of factors, ranging from barriers to access to non-VA systems, to characteristics of the VA delivery system itself, to need for treatment. 相似文献
94.
Jeffrey T Cope MD Michael C Mauney MD David Banks BS Oliver A.R Binns MD Christopher L Moore BS Jeffrey J Rentz BS Kimberly S Shockey MS R.Christoper King MD Irving L Kron MD Curtis G Tribble MD 《The Annals of thoracic surgery》1997,63(6)
Background. Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non–heart-beating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning.Methods. Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non–heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 μg/kg (n = 7) before initiation of apnea. Non–heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia.Results. Phenylephrine 25 μg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 ± 0.5 versus 7.7 ± 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 ± 5.3 versus 41.0 ± 3.4 mm Hg; p = 0.04). Phenylephrine 25 μg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09).Conclusions. Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.(Ann Thorac Surg 1997;63:1664–8) 相似文献
95.
96.
97.
Teresa S. Priebe Edward N. Atkinson Bih-Fang Pan J. Arly Nelson 《Cancer chemotherapy and pharmacology》1992,29(6):485-489
Summary PANC02 is a ductal adenocarcinoma of the pancreas that is resistant to every known class of clinically active antitumor agent. To study the mechanism(s) underlying the intrinsic drug resistance of this tumor, a mammary adenocarcinoma (CA-755) that also grows in C57/BL mice and is known to be drugsensitive was used for comparison. PANC02 resistance and CA-755 sensitivity to several antitumor agents and to X-ray therapy was confirmed in mice, and PANC02 also demonstrated relative resistance in tissue culture. Relative to Chinese hamster ovary (CHO) and CA-755 cells, PANC02 did not appear to show a higher rate of mutation to drug resistance in culture as based on the 6-thioguanine resistance marker. Although P-glycoprotein characteristic of the multidrug resistance (MDR) phenomenon could be demonstrated at the mRNA level using a sensitive RNAse protection assay, the level of expression found was several orders of magnitude lower than that observed in phenotypic MDR cell lines. Furthermore, quinidine failed to increase the sensitivity of PANC02 cells to Adriamycin under conditions that clearly potentiated the toxicity of the drug to a CHO cell line exhibiting classic MDR traits. The heterogeneity in the distribution of drugs was inferred as being significantly greater in PANC02 versus CA-755 cells in vivo as based on measurements of within-animal, within-tumor variance in the distribution of the marker compounds inulin and antipyrine. Although it may not be the only mechanism involved, this greater intratumor heterogeneity in drug distribution could theoretically play a major role in the intrinsic drug resistance of PANC02 in vivo.Supported by grant CH-458 from the American Cancer Society, by grant CA-28034 from the National Cancer Institute, and in part by Cancer Center Core Support grant, NIH-NCI-CA-16672. Animals were maintained in facilities approved by the American Association for Accreditation of Laboratory Animal Care and in accordance with current United States Department of Agriculture, Department of Health and Human Services, and National Institutes of Health regulations and standards 相似文献
98.
99.
Yair Lotan Matthew T Gettman Claus G Roehrborn Margaret S Pearle Jeffrey A Cadeddu 《JSLS, Journal of the Society of Laparoendoscopic Surgeons》2003,7(2):111-115
BACKGROUND AND OBJECTIVES: To evaluate the experience with laparoscopic nephrectomy in a large county hospital and perform a cost comparison between uncomplicated open and laparoscopic nephrectomy. METHODS: Eleven consecutive patients who underwent an uncomplicated laparoscopic nephrectomy in a large county hospital were compared with 8 patients who underwent uncomplicated open nephrectomy during the same period. Patient charts and corresponding billing records were reviewed to determine overall hospitalization cost and individual cost components. RESULTS: No perioperative complications occurred in either the laparoscopic or open group, and no statistically significant differences existed between groups with regard to patient demographics or operative parameters. The overall operating room costs favored the open nephrectomy group by dollars 1070 (P=0.003). However, the overall cost of hospitalization, surgeon professional fees, duration of hospitalization, room and board costs, laboratory, and radiology costs, pharmacy costs, intravenous solution and infusion pump costs all significantly favored the laparoscopic patient group. The mean difference in overall hospital cost between laparoscopic and open nephrectomy was dollars 1211 in favor of laparoscopy (P=0.037). CONCLUSIONS: Our experience with laparoscopic nephrectomy in a large county hospital demonstrates a clear economic advantage in favor of the laparoscopic approach. Given limited funding for public hospitals and a clear patient benefit, laparoscopic nephrectomy should constitute first-line therapy when nephrectomy is indicated. 相似文献
100.
Howard Weinstein Michael A. King Christopher P. Reinhardt Brenda A. McSherry Jeffrey A. Leppo 《Journal of nuclear cardiology》1994,1(1):39-51