全文获取类型
收费全文 | 60380篇 |
免费 | 4101篇 |
国内免费 | 249篇 |
专业分类
耳鼻咽喉 | 653篇 |
儿科学 | 1235篇 |
妇产科学 | 1434篇 |
基础医学 | 7628篇 |
口腔科学 | 811篇 |
临床医学 | 5723篇 |
内科学 | 14289篇 |
皮肤病学 | 609篇 |
神经病学 | 5678篇 |
特种医学 | 2333篇 |
外科学 | 9508篇 |
综合类 | 759篇 |
一般理论 | 65篇 |
预防医学 | 3987篇 |
眼科学 | 995篇 |
药学 | 3750篇 |
中国医学 | 163篇 |
肿瘤学 | 5110篇 |
出版年
2023年 | 290篇 |
2022年 | 329篇 |
2021年 | 1602篇 |
2020年 | 992篇 |
2019年 | 1437篇 |
2018年 | 1880篇 |
2017年 | 1278篇 |
2016年 | 1357篇 |
2015年 | 1644篇 |
2014年 | 2403篇 |
2013年 | 2885篇 |
2012年 | 4890篇 |
2011年 | 4865篇 |
2010年 | 2770篇 |
2009年 | 2454篇 |
2008年 | 4243篇 |
2007年 | 4400篇 |
2006年 | 4274篇 |
2005年 | 4116篇 |
2004年 | 3660篇 |
2003年 | 3341篇 |
2002年 | 3043篇 |
2001年 | 576篇 |
2000年 | 491篇 |
1999年 | 526篇 |
1998年 | 540篇 |
1997年 | 494篇 |
1996年 | 413篇 |
1995年 | 355篇 |
1994年 | 295篇 |
1993年 | 261篇 |
1992年 | 270篇 |
1991年 | 217篇 |
1990年 | 180篇 |
1989年 | 134篇 |
1988年 | 130篇 |
1987年 | 111篇 |
1986年 | 118篇 |
1985年 | 123篇 |
1984年 | 154篇 |
1983年 | 113篇 |
1982年 | 140篇 |
1981年 | 120篇 |
1980年 | 99篇 |
1979年 | 55篇 |
1978年 | 61篇 |
1977年 | 60篇 |
1976年 | 52篇 |
1975年 | 40篇 |
1974年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Denise Haderski Sergey Nazarenko Chih-Min Cheng Anne Hiltner Eric Baer 《Macromolecular chemistry and physics.》1995,196(8):2545-2561
The crystallization behavior of coextruded microlayered sheets comprised of 657 alternating layers of polycarbonate (PC) and a miscible copolyester of mainly 1,4-cyclohexanedimethanol and terephthalic acid (KODAR) was investigated as a function of annealing time when the KODAR was crystallized isothermally from the glass at 195°C. Comparisons were made with crystallization of KODAR alone, and with crystallization of KODAR from melt blends with PC. The kinetics of crystallization and the morphology of the crystallized KODAR were characterized with differential scanning calorimetry, and by examination of thin sections microtomed from annealed specimens in the polarized light microscope and the transmission electron microscope. The growth rate of small, birefringent KODAR spherulites was non-linear, and was strongly affected by diffusion of PC into the KODAR layers. Diffusion of amorphous PC into the KODAR layers retarded nucleation and spherulite growth and decreased spherulite density. The effect became more pronounced as the KODAR layer thickness was reduced. Spherulities nucleated randomly throughout the KODAR layers in the PC/KODAR 20/80 (w/w) microlayer and grew rapidly to form a continuous layer of impinged spherulites. In contrast, spherulites in the PC/KODAR 40/60 and 60/40 microlayers nucleated and grew along the center of the KODAR layers where the KODAR concentration was highest. 相似文献
92.
Twenty-two infants of isolated ventricular septal defect with congestive heart failure were fed with lower-sodium content formula-Lonalac (Mead-Johnson) to study the clinical response of treatment for congestive heart failure. There were no significant changes of intake, urinary output, serum sodium, potassium and osmolality before, 2 days and 6 days after Lonalac feeding. The low sodium content formula may feed the infants with congestive heart failure in addition to the traditional anticongestive therapy. 相似文献
93.
94.
Robert C. Flanigan Joseph H. Saiers Michael Wolf Eric H. Kraut Anthony Y. Smith Brent Blumenstein E. David Crawford 《Investigational new drugs》1994,12(2):147-149
Summary The Southwest Oncology Group (SWOG) studied the response rate and toxicity of merbarone (1,000 mg/m2 IV continuous infusion days 1–5, q 21 days) in patients with advanced metastatic renal cell carcinoma. Among 36 eligible patients, there was one partial response for a response rate of 3% (95% C.I. 0.1–15%). There were no mixed responses. There were no treatment related deaths or adverse drug reactions. Significant anemia, diarrhea, and hypercalcemia were observed. Mild to moderate degrees of malaise/fatigue/lethargy, dizziness/vertigo, hyperglycemia, creatinine increase, nausea, vomiting, weight loss, pedal edema, dyspnea, and granulocytopenia were noted. Merbarone does not have significant activity as a single agent in advanced renal cell carcinoma. 相似文献
95.
96.
Juraj Sprung MD PhD David Distel CRNA Jeffrey Grass MD Eric L. Bloomfield MD Ian C. Lavery MD 《Journal of clinical anesthesia》1996,8(8):662-665
We describe a patient in whom long-term monoamine oxidase (MAO) inhibitor therapy was discontinued 20 days before surgery with general anesthesia. This patient developed severe perioperative hypotension after administration of 10 mg of bupivacaine through an epidural catheter, which was corrected only after potent vasopressor therapy. We attribute this hemodynamic instability to attenuation of this patient's sympathetic tone based on several mechanisms: (1) residual effect of long-term administration of MAO inhibitor that caused a decrease in the number of β-adrenergic receptors (adrenergic subsensitivity due to receptor down-regulation), (2) recovered MAO activity causing effective degradation of sympathetic amines, and (3) combined attenuating effects of general and epidural anesthesia on sympathetic tone. 相似文献
97.
Frenna V Santos L Ohana E Bailey C Wattiez A 《Journal of minimally invasive gynecology》2007,14(2):169-171
STUDY OBJECTIVE: Ureteral endometriosis is rare, accounting for less than 0.3% of all endometriotic lesions. The aim of our study is to evaluate the prevalence of extrinsic ureteral endometriosis in women undergoing laparoscopic surgery for severe endometriosis and to suggest that laparoscopic ureterolysis represents a mandatory measure in all cases to avoid ureteral injury. METHODS: A retrospective analysis was performed of all cases of patients who underwent laparoscopic surgery for severe endometriosis at the departments of obstetrics and gynecology at CMCO-SIHCUS and Hautepierre Hospital, Strasbourg, from November 2004 through January 2006. MEASUREMENTS AND MAIN RESULTS: We recorded 54 patients with a mean age of 31 years and a mean body mass index of 21.9. Reported symptoms were dysmenorrhea (88%), severe dyspareunia (88%), severe pelvic pain (38.8%), and infertility (74%). Five women presented with dysuria, frequency, recurrent urinary tract infections, and pain in the renal angle, and 2 patients had hydronephrosis. We observed 3 patients (5.6%) with ureteral stenosis, 35 (64.8%) with adenomyotic tissue surrounding the ureter without stenosis, and 16 (29.6%) with adenomyotic tissue adjacent to the ureter. It was on the left side in 47.4% of cases, on the right side in 31.6% cases, and bilaterally in 21% of cases. In 9 patients, ureteral involvement was associated with bladder endometriosis (16.7%). In all patients, ureterolysis was performed. There was 1 case of ureteral injury during the procedure, 2 of transitory urinary retention, and 1 of uretero-vaginal fistula after surgery. During the first year of follow-up, the disease recurred in 4 patients, with no evidence of the disease in the urinary tract. CONCLUSION: Conservative laparoscopic surgery to relieve ureteral obstruction and remove pathologic tissue is the management of choice. Resection of part of the ureter should be performed only in exceptional cases. Ureterolysis should be performed in all patients before endometriotic nodule resection to recognize and prevent any ureteral damage. 相似文献
98.
J Douglas Bremner Meena Vythilingam Eric Vermetten George Anderson John W Newcomer Dennis S Charney 《Neuropsychopharmacology》2004,55(8):811-815
BACKGROUND: Major depression has been associated with hypercortisolemia in a subset of patients with depression. Administration of exogenous cortisol and other glucocorticoids to healthy human subjects has been observed to result in a transient impairment in verbal declarative memory function. The purpose of this study was to assess the effects of the glucocorticoid, dexamethasone, on verbal declarative memory function in patients with untreated unipolar major depressive disorder (MDD). METHODS: Fifty two men and women with (n = 28) and without (n = 24) MDD received placebo or dexamethasone (1 mg and 2 mg on 2 successive days) in a double-blind, randomized fashion. Declarative memory was assessed with paragraph recall at baseline (day 1) and day 3. RESULTS: There was a significant interaction between diagnosis and drug (dexamethasone vs. placebo) on paragraph recall. In the healthy subjects, memory improved from baseline to day 3 with placebo and was unchanged with dexamethasone, whereas in MDD patients memory function showed a pattern of decreasing with placebo and improving with dexamethasone from baseline to day 3. CONCLUSIONS: These findings are consistent with an altered sensitivity of declarative memory function in MDD to regulation by glucocorticoids. Possible explanations of the findings include alterations in glucocorticoid receptors in the hippocampus or other brain regions mediating declarative memory, or differential sensitivity to dexamethasone-induced reductions in cortisol, in patients with MDD. 相似文献
99.
100.
Prevalence of silent myocardial ischemia in asymptomatic individuals with subclinical atherosclerosis detected by electron beam tomography 总被引:3,自引:0,他引:3
Anand D. Vijay Lim Eric Raval Usha Lipkin David Lahiri Avijit 《Journal of nuclear cardiology》2004,11(4):450-457
BACKGROUND: Electron beam tomography coronary calcium imaging is an evolving technique for the early detection of coronary atherosclerosis, and recent studies have established its prognostic value in asymptomatic individuals. The relationship of coronary artery calcium scores (CAC) to obstructive coronary artery disease (CAD) has been poorly studied but is clinically relevant because it determines which individuals are likely to benefit from revascularization procedures. Hence, we prospectively evaluated the prevalence of myocardial ischemia in asymptomatic patients with cardiovascular risk factors and subclinical atherosclerosis. METHODS AND RESULTS: We studied 864 asymptomatic patients with no previous CAD but with cardiovascular risk factors, referred for electron beam tomography coronary calcium imaging to our institution over an 18-month period. From this group, 220 consecutive patients (85% men; mean age, 61 +/- 9 years; age range, 31-84 years) with moderate to severe atherosclerotic disease (coronary calcium score > or =100 Agatston units) were prospectively evaluated by technetium 99m sestamibi single photon emission computed tomography (SPECT). Patients were followed up (mean follow-up, 14 months) and data regarding their subsequent clinical management recorded. Of the 220 patients, 119 had moderate atherosclerosis (CAC score of 100-400 Agatston units) and 101 had severe atherosclerosis (CAC score > or =400 Agatston units). Abnormal SPECT findings were seen in 18% of patients with moderate atherosclerosis (n = 21) and 45% of patients with severe atherosclerosis (n = 45). Increasing severity of atherosclerosis was related to increasing ischemic burden (summed difference score = 1 +/- 0.2 for CAC score of 100-400 Agatston units and 3.2 +/- 0.5 for CAC score > or =400 Agatston units). In a multivariate linear regression model incorporating risk factors, CAC was the only predictor of silent ischemia. CONCLUSION: In comparison to previously published data, we detected a higher prevalence of silent ischemia even in patients with moderate coronary atherosclerosis (18%). This may reflect the differing risk factor profile of our patient population. When coronary calcium screening is used to preselect asymptomatic patients with cardiovascular risk factors for myocardial perfusion imaging, the optimum coronary calcium score threshold will depend on the population prevalence of risk factors and asymptomatic obstructive CAD. 相似文献