全文获取类型
收费全文 | 77645篇 |
免费 | 5816篇 |
国内免费 | 653篇 |
专业分类
耳鼻咽喉 | 1294篇 |
儿科学 | 1425篇 |
妇产科学 | 1587篇 |
基础医学 | 11914篇 |
口腔科学 | 1490篇 |
临床医学 | 7041篇 |
内科学 | 15272篇 |
皮肤病学 | 2257篇 |
神经病学 | 6408篇 |
特种医学 | 4306篇 |
外科学 | 10375篇 |
综合类 | 808篇 |
现状与发展 | 1篇 |
一般理论 | 25篇 |
预防医学 | 4364篇 |
眼科学 | 2066篇 |
药学 | 6647篇 |
1篇 | |
中国医学 | 678篇 |
肿瘤学 | 6155篇 |
出版年
2023年 | 457篇 |
2022年 | 1201篇 |
2021年 | 2058篇 |
2020年 | 1124篇 |
2019年 | 1804篇 |
2018年 | 2022篇 |
2017年 | 1612篇 |
2016年 | 2158篇 |
2015年 | 2936篇 |
2014年 | 3525篇 |
2013年 | 4109篇 |
2012年 | 5974篇 |
2011年 | 5786篇 |
2010年 | 3563篇 |
2009年 | 3074篇 |
2008年 | 4312篇 |
2007年 | 4191篇 |
2006年 | 3815篇 |
2005年 | 3624篇 |
2004年 | 3174篇 |
2003年 | 2801篇 |
2002年 | 2542篇 |
2001年 | 1747篇 |
2000年 | 1695篇 |
1999年 | 1404篇 |
1998年 | 585篇 |
1997年 | 537篇 |
1996年 | 465篇 |
1995年 | 430篇 |
1994年 | 360篇 |
1993年 | 356篇 |
1992年 | 835篇 |
1991年 | 803篇 |
1990年 | 702篇 |
1989年 | 746篇 |
1988年 | 719篇 |
1987年 | 674篇 |
1986年 | 585篇 |
1985年 | 563篇 |
1984年 | 466篇 |
1983年 | 375篇 |
1982年 | 293篇 |
1981年 | 265篇 |
1980年 | 240篇 |
1979年 | 350篇 |
1978年 | 299篇 |
1977年 | 229篇 |
1974年 | 238篇 |
1973年 | 252篇 |
1972年 | 218篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
J M G Crane T Delaney K D Butt K A Bennett D Hutchens D C Young 《The journal of maternal-fetal & neonatal medicine》2004,15(5):319-323
OBJECTIVE: To identify independent predictors of successful labor induction with oral or vaginal misoprostol. METHODS: Women enrolled in four previous randomized trials involving oral or vaginal misoprostol for cervical ripening and labor induction were included in the present cohort study, with dosing of 25-50 microg every 4 to 6 h vaginally (n = 574) or 50 microg every 4 h orally (n = 207). Multiple logistic regression was performed to identify factors independently associated with successful labor induction -- defined as vaginal delivery within 12 h, vaginal delivery within 24 h and spontaneous vaginal delivery. Predictors of Cesarean birth and the need for only one dose of misoprostol were also identified. Variables included in the models were maternal age, weight, height, parity, gravidity, membrane status, route of misoprostol, gestational age, birth weight, and Bishop score and its individual components. RESULTS: Maternal age, height, weight, parity, birth weight, dilatation, effacement and cervical station were associated with vaginal delivery within 24 h of induction. Maternal age, height, weight, nulliparity, birth weight and route of misoprostol were associated with Cesarean birth, with oral misoprostol being associated with a lower rate of Cesarean birth. The need for only one dose of misoprostol was predicted by maternal height, weight, parity, gestational age, Bishop score and route of misoprostol. CONCLUSION: Characteristics of the woman (height, weight, parity), the fetus (birth weight) and some of the individual components of the Bishop score, were associated with successful labor induction, with oral misoprostol being associated with a lower rate of Cesarean birth. 相似文献
192.
The common ultrasonographic features of pilomatricoma. 总被引:3,自引:0,他引:3
OBJECTIVES: The purpose of this series was to describe typical ultrasonographic features of 20 cases of pilomatricoma and to improve its diagnostic rate with the use of an ultrasonographic approach. METHODS: For 20 pilomatricomas in 19 patients with preoperative ultrasonography from 1995 to 2004, we reviewed age, sex, symptoms, duration, referring clinician, and tumor sites. The ultrasonographic findings were retrospectively analyzed for tumor location, shape, size, margin, echo texture, echogenicity, presence, amount, and shape of calcification, presence of a hypoechoic rim, and Doppler flow pattern. RESULTS: The mean age of the 19 patients was 6.9 years (range, 1-21 years), and the female-male ratio was 1.1:1. Patients had a painful palpable mass in 10 cases (50%). Nine lesions occurred in the neck, 5 in the cheek, 2 in the preauricular region, and 4 in the extremity. All tumors were located in the subcutaneous layer. The mean size of the tumors was 13.4 mm. Fourteen pilomatricomas (70%) appeared as well-defined oval masses. Tumors were heterogeneously hyperechoic in 80% of cases. All tumors had internal echogenic foci. A hypoechoic rim was seen in 17 cases (85%). Doppler flow signals were observed in the peripheral region in 14 cases (70%). A correct preoperative diagnosis was made in 33% on the basis of clinical findings and in 76% by ultrasonography. CONCLUSIONS: Diagnosis of pilomatricoma should be considered when a well-defined mass with inner echogenic foci and a peripheral hypoechoic rim or a completely echogenic mass with strong posterior acoustic shadowing in the subcutaneous layer of the head, neck, or extremity is found on ultrasonography. 相似文献
193.
Jong Hun Kim Kwang-Yeol Park Sang Won Seo Duk L. Na Chin-Sang Chung Kwang Ho Lee Gyeong-Moon Kim 《JOURNAL OF CLINICAL NEUROLOGY》2007,3(1):62-66
The retrosplenial cortex is a cytoarchitecturally distinct brain structure located in the posterior cingulate gyrus and bordering the splenium, precuneus, and calcarine fissure. Functional imaging suggests that the retrosplenium is involved in memory, visuospatial processing, proprioception, and emotion.We report on a patient who developed reversible verbal and visual memory deficits following a stroke. Neuropsychological testing revealed both anterograde and retrograde memory deficits in verbal and visual modalities. Brain diffusion-weighted and T2-weighted magnetic resonance imaging (MRI) demonstrated an acute infarction of the left retrosplenium. 相似文献
194.
195.
A commercially available ADAC Pinnacle(3) radiation treatment planning system has been used to model electron beams from a Varian Clinac 2300C/D in the energy range of 6 to 22 MeV. Prior to clinical use, the dosimetric characteristics of the beams have to be modeled accurately. As a first step for beam modeling, a number of dose profile and depth dose measurements were taken at standard source-to-surface distance (SSD) of 100 cm. Dose profiles and depth dose measurements at extended SSDs up to 120 cm are important for ascertaining accuracy of the model, as well as their clinical usefulness in the treatment of some sites (e.g., head-and-neck tumors). Modeled and measured beam data were compared. Over 98% of comparison points (modeled vs. measured) at 100-cm SSD were within 2.5% or 2.5 mm. At 110 cm SSD, over 98% of compared points were within 4% or 4 mm, and at 120-cm SSD, over 98% of compared points were within 5% or 5 mm. Overall, more than 98% of compared points were within 4% or 4 mm. Better models were produced for lower energies (6 to 15 MeV) than higher energies (18 and 22 MeV). For 6, 9, 12, and 15 MeV, 89% of compared points were within 2% or 2 mm. For 18- and 22-MeV electron energies, 75% and 67%, respectively, were within 2% or 2 mm. These results are consistent with the recommendations of AAPM Task Group Report 53. 相似文献
196.
D Young 《British journal of hospital medicine》1990,44(6):413-415
The pulmonary artery flow-directed catheter (Swan-Ganz catheter) has been in clinical use for 20 years. These devices are now used by 80% of UK intensive care units for the diagnosis and monitoring of a wide range of cardiorespiratory problems. The principal indications for the use of pulmonary artery catheters and the evidence supporting these indications are outlined in this article. 相似文献
197.
Hy De Lee Euy Young Soh Hoon Sang Chi Byong Ro Kim Kyong Sik Lee Kyung Soon Song Hyun Joo Jung 《Surgery today》1990,20(2):180-185
The relationship between primary tumor proliferative activity and clinical and pathologic characteristics was analyzed in
relation to menopausal status in 32 patients with malignant or benign breast disease. The thymidine labeling index (TLI) showed
significantly higher median values in the cancer patients (3.48 per cent) than in the patients with benign diseases (1.02
per cent). TLI was not significantly affected by delayed incubation at room temperature for about 1 hour. In the breast cancer
patients, TLI did not significantly correlate to tumor size, the presence of axillary lymph node metastasis or pathologic
nuclear grading. The only significant difference was limited to the breast cancer patients without axillary lymph node metastasis
in relation to menopausal status; the TLI in the premenopausal patients (5.10 per cent) was significantly higher (p<0.05)
than that in the postmenopausal patients (2.28 per cent). These data thus suggest that among premenopausal patients without
axillary lymph node metastasis, those with a high TLI could be potential candidates for adjuvant chemotherapy. 相似文献
198.
199.
Acute exposure to a neurotoxin, 3-nitropropionic acid (3-NPA), in rats results in an increase in total free fatty acid (FFA) concentration in selective brain regions. We investigated the effect of 3-NPA administration on the cerebral concentrations of FFA used as a marker of oxidative stress. Rats (n=3/group) were dosed subcutaneously (s.c.) either with a vehicle (phosphate buffer) or 3-NPA in phosphate buffer at 30 mg/kg body weight. Animals were sacrificed after 1, 2, 3, and 6 h of injection. Brains were then dissected into frontal cortex (FC), caudate nucleus (CN), and hippocampus (HIP). The concentration of total FFA increased from 130 to 300% within 1–2 h after 3-NPA injection in all brain regions when compared with the baseline level obtained from the control rats and taken as 100%. In CN, FFA returned to the baseline level within 3 h of treatment. However, in FC and HIP the concentration of FFA remained significantly elevated above the baseline until 6 h. The released FFA provide a substrate for free radicals formation. The results of this study suggest a role of oxidative stress in the mechanism of 3-NPA toxicity. 相似文献
200.
A R Burgess B J Eastridge J W Young T S Ellison P S Ellison A Poka G H Bathon R J Brumback 《The Journal of trauma》1990,30(7):848-856
From January 1, 1985, to September 10, 1988, 210 consecutive patients with high-energy pelvic ring disruptions (exclusive of acetabular fractures) were admitted to a statewide referral center for adult multiple trauma. They were treated by one of four attending orthopaedic traumatologists per protocol as determined by their injury classification and hemodynamic status; the injury classification system was based on the vector of force involved and the quantification of disruption from that force, i.e., lateral compression, anteroposterior compression, vertical shear, and combined mechanical injury. Of the 210 patients, 162 had complete charts: 126 (78.0%) were admitted directly from the scene, 110 (67.9%) were injured in motor vehicle or motorcycle accidents, 25 (15.0%) were admitted in shock (blood pressure less than 90 mm Hg), the average Glasgow Coma Score was 13.2, and the average Injury Severity Score was 25.8. Treatment of the pelvic fracture included the following methods (alone or in combination): acute external fixation (45.0; 28.0%), open reduction/internal fixation (22; 13.5%), acute arterial embolization (11; 7.0%), and bedrest (68; 42.0%). Overall blood replacement averaged 5.9 units (lateral compression, 3.6 units; anteroposterior compression, 14.8 units; vertical shear, 9.2 units; combined mechanical, 8.5 units). Overall mortality was 8.6% (lateral compression, 7.0%; anteroposterior, 20.0%, vertical shear, 0%; combined mechanical, 18.0%). The cause of death was associated with the pelvic fracture in less than 50%; no patient with an isolated or vertical shear pelvic injury died. We conclude that the predictive value of our classification system (incorporating appreciation of the causative forces and resulting injury patterns) and our classification-based treatment protocols reduce the morbidity and mortality related to pelvic ring disruption. 相似文献