全文获取类型
收费全文 | 1378篇 |
免费 | 73篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 71篇 |
妇产科学 | 33篇 |
基础医学 | 149篇 |
口腔科学 | 45篇 |
临床医学 | 110篇 |
内科学 | 336篇 |
皮肤病学 | 24篇 |
神经病学 | 33篇 |
特种医学 | 419篇 |
外科学 | 85篇 |
综合类 | 39篇 |
预防医学 | 25篇 |
眼科学 | 6篇 |
药学 | 40篇 |
1篇 | |
肿瘤学 | 31篇 |
出版年
2023年 | 6篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 15篇 |
2016年 | 10篇 |
2015年 | 15篇 |
2014年 | 33篇 |
2013年 | 35篇 |
2012年 | 20篇 |
2011年 | 28篇 |
2010年 | 34篇 |
2009年 | 51篇 |
2008年 | 23篇 |
2007年 | 37篇 |
2006年 | 31篇 |
2005年 | 25篇 |
2004年 | 16篇 |
2003年 | 21篇 |
2002年 | 9篇 |
2001年 | 17篇 |
2000年 | 9篇 |
1999年 | 17篇 |
1998年 | 78篇 |
1997年 | 79篇 |
1996年 | 79篇 |
1995年 | 64篇 |
1994年 | 39篇 |
1993年 | 58篇 |
1992年 | 6篇 |
1991年 | 12篇 |
1990年 | 24篇 |
1989年 | 53篇 |
1988年 | 41篇 |
1987年 | 48篇 |
1986年 | 54篇 |
1985年 | 69篇 |
1984年 | 38篇 |
1983年 | 30篇 |
1982年 | 31篇 |
1981年 | 32篇 |
1980年 | 40篇 |
1979年 | 8篇 |
1978年 | 19篇 |
1977年 | 24篇 |
1976年 | 22篇 |
1975年 | 20篇 |
1914年 | 1篇 |
排序方式: 共有1455条查询结果,搜索用时 31 毫秒
61.
Simultaneous sonography and quantitative serum human chorionic gonadotropin (HCG) levels from 126 women with threatened abortion were compared. Of 56 women with normal outcome, 39 (70%) had a gestation sac greater than or equal to 5 mm in mean sac diameter, and in each case the HCG level was 1,800 milli-international units (mIU/ml) or greater. The serum HCG levels strongly correlated with the gestation sac sizes to a mean sac diameter of 25 mm. Of 70 abnormal pregnancies, 31 demonstrated a gestation sac. Of these, 20 women (65%) had disproportionately low HCG levels relative to sac size, including 12 in whom the HCG level was less than 1,800 mIU/ml. One woman with an early molar pregnancy had a disproportionately elevated HCG level. Correlation of sonograms with a simultaneous measurement of serum HCG level is a useful method for evaluating threatened spontaneous abortion. A disproportionately low HCG level relative to gestation sac size is evidence for an abnormal pregnancy. 相似文献
62.
Role of point A in the era of computerized dosimetry 总被引:1,自引:0,他引:1
63.
In 44 patients with one or more calculi in the upper two-thirds of the ureter, single-stage percutaneous nephrolithotomy was performed through a middle or upper calyceal nephrostomy after cystoscopic placement of an occlusion balloon catheter distal to the calculus; in 42, the procedure was successful. The occlusion balloon catheter permitted retrograde opacification of all systems for enhanced renal puncture. In the last 30 patients an attempt was made either to push the calculus upward mechanically or to flush it upward into the renal pelvis with carbon dioxide or dilute contrast material. This was successful in 24 of these patients. Prior overnight occlusion of the ureter by means of ureteral dilatation further facilitates dislodgment of the calculus, which was successful in 12 of 13 patients. 相似文献
64.
A R Glass R A Vigersky R Rajatanavin W Pardridge R C Smallridge L Wartofsky K D Burman 《Endocrinology》1984,114(5):1745-1753
Traditionally, it has been thought that the bioavailable fraction of circulating serum hormones, i.e. that which is available for cellular uptake and is physiologically active, is limited to the free (nonprotein bound) hormone. However, recent evidence, based on acute organ uptake of labeled hormone, suggests that the amount of hormone which is bioavailable in vivo may exceed that which is calculated to be free in vitro. To explore the bioavailability of circulating protein-bound thyroid hormones under steady state conditions in vivo, we altered serum thyroid hormone-binding proteins in rats by inducing nephrotic syndrome with puromycin aminonucleoside. Nephrotic rats (serum albumin, 1.1 g/dl) were found to have a marked reduction in serum T4 [2.1 +/- 0.2 (SEM) vs. 6.5 +/- 0.3 microgram/dl; P less than 0.01] and an elevation of serum T3 [141 +/- 8 vs. 51 +/- 2 ng/dl; P less than 0.01]. Estimated T4 production rate was normal in nephrotic rats, and the 3- to 4-fold increase in T4 MCR appeared to account for the marked reduction in serum T4. By contrast, increased serum T3 levels in nephrotic rats reflected both a reduction (55%) in T3 MCR and an increased rate of peripheral conversion of T4 to T3. A circulating inhibitor of T4 binding to serum proteins appeared to be present in nephrotic rats. The changes in the various serum components of thyroid hormone [T4-binding prealbumin (TBPA)-bound, albumin-bound, free] produced by nephrotic syndrome were compared with the corresponding changes in indices of thyroid hormone bioavailability (MCR, urinary excretion, hepatic content, TSH suppression, single pass extraction by liver). These comparisons suggested that nephrotic syndrome results in increased bioavailability of circulating T4 and decreased bioavailability of circulating T3. The bioavailable fraction of circulating T3 in vivo seemed to include both free T3 and that which is albumin bound in vitro. The bioavailable fraction of circulating T4 resembled free T4 more than non-TBPA-bound T4 (= albumin bound + free), although a nephrosis-induced increase in bioavailability of TBPA-bound T4 was also possible. We conclude that nephrotic rats have low serum T4, which is related to accelerated T4 clearance, and high serum T3, which is related both to decreased T3 clearance and increased peripheral conversion of T4 to T3. Under steady state conditions in vivo, bioavailable circulating T3 appears to include both free T3 and the T3 that is bound to albumin in vitro. 相似文献
65.
Brandon JC; Teplick SK; Haskin PH; Sammon JK; Muhr WF; Hofmann AF; Gambescia RA; Zitomer N 《Radiology》1988,166(3):665-667
The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control. 相似文献
66.
Widespread Castleman disease: CT and US findings 总被引:4,自引:0,他引:4
The widespread form of Castleman disease is a rare condition that has been recognized only recently as a disease with an aggressive, often malignant course. The authors present computed tomographic (CT) findings in six patients with this condition and ultrasound (US) findings in four of the six. CT demonstrated splenomegaly and retroperitoneal lymphadenopathy in all six patients. In one patient, CT also showed additional widespread mesenteric and peripancreatic lymphadenopathy, a large mesenteric mass adherent to the descending colon in another, and mediastinal lymphadenopathy in a third. Three patients had peripheral axillary or inguinal lymphadenopathy. Enlarged lymph nodes were 1-4 cm in diameter, and none displayed contrast enhancement on CT scans obtained with drip infusion of contrast media. On US scans, the nodes were poorly echogenic in all four cases. In no case was focal liver or splenic infiltration seen on either CT or US scans. 相似文献
67.
MR Danzig RA Ghandour P Chang AA Wagner PM Pierorazio ME Allaf JM McKiernan 《Urologic oncology》2017,35(3):116
Purpose
We compared renal function outcomes among patients in the surveillance and intervention arms of the DISSRM registry.Materials and methods
Patients were grouped into chronic kidney disease stages by estimated glomerular filtration rate range. Cases were considered up staged if a more advanced chronic kidney disease stage was entered during followup. Chronic kidney disease up staging-free survival was compared among groups using Kaplan-Meier analysis and paired comparisons log rank tests. Multivariate Cox regression identified independent predictors of chronic kidney disease up staging-free survival.Results
A total of 162 patients met the study inclusion criteria, with 68 in the surveillance arm, 65 undergoing partial nephrectomy, 15 undergoing radical nephrectomy, and 14 undergoing cryoablation. Median tumor size was 2.2 cm. Mean estimated glomerular filtration rate change was significantly larger for radical nephrectomy vs. surveillance (?9.2 vs. ?0.5 ml/min/1.73 m2) and for radical vs. partial nephrectomy (?9.2 vs. ?1.9 ml/min/1.73 m2) (P = 0.001). No other groups differed significantly. On Kaplan-Meier analysis, patients undergoing radical nephrectomy had significantly worse chronic kidney disease up staging-free survival vs. those treated with partial nephrectomy (P = 0.029), surveillance (P = 0.007), and cryoablation (P = 0.019). No other groups differed significantly. On multivariate analysis, radical nephrectomy independently predicted poor chronic kidney disease up staging-free survival (odds ratio vs. surveillance 30.6, P = 0.001). Neither partial nephrectomy (P = 0.985) nor cryoablation (P = 0.976) predicted poor chronic kidney disease up staging-free survival relative to surveillance.Conclusions
Patients in the surveillance arm had superior estimated glomerular filtration rate preservation compared to those in the radical nephrectomy but not the partial nephrectomy arm. In certain patients with small renal masses, surveillance and partial nephrectomy may offer comparable renal functional outcomes. This could be partly attributable to a modest estimated glomerular filtration rate decrease associated with surveillance itself. A thorough understanding of the renal functional impacts of treatment modalities is critical in the management of small renal masses. 相似文献68.
69.
RA Stein 《Clinical genetics》2009,76(1):21-23
15q13.3 microdeletions increase risk of idiopathic generalized epilepsy
Helbig et al. (2009)
Nature Genetics 41(2):160–162 相似文献
Helbig et al. (2009)
Nature Genetics 41(2):160–162 相似文献
70.