全文获取类型
收费全文 | 4292篇 |
免费 | 293篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 49篇 |
儿科学 | 368篇 |
妇产科学 | 108篇 |
基础医学 | 618篇 |
口腔科学 | 70篇 |
临床医学 | 410篇 |
内科学 | 1013篇 |
皮肤病学 | 29篇 |
神经病学 | 301篇 |
特种医学 | 545篇 |
外国民族医学 | 1篇 |
外科学 | 422篇 |
综合类 | 84篇 |
一般理论 | 2篇 |
预防医学 | 182篇 |
眼科学 | 114篇 |
药学 | 140篇 |
中国医学 | 5篇 |
肿瘤学 | 157篇 |
出版年
2021年 | 32篇 |
2020年 | 26篇 |
2019年 | 35篇 |
2018年 | 54篇 |
2017年 | 36篇 |
2016年 | 52篇 |
2015年 | 59篇 |
2014年 | 69篇 |
2013年 | 123篇 |
2012年 | 134篇 |
2011年 | 137篇 |
2010年 | 139篇 |
2009年 | 98篇 |
2008年 | 113篇 |
2007年 | 122篇 |
2006年 | 118篇 |
2005年 | 100篇 |
2004年 | 114篇 |
2003年 | 104篇 |
2002年 | 92篇 |
2001年 | 104篇 |
2000年 | 131篇 |
1999年 | 115篇 |
1998年 | 164篇 |
1997年 | 145篇 |
1996年 | 148篇 |
1995年 | 116篇 |
1994年 | 99篇 |
1993年 | 103篇 |
1992年 | 105篇 |
1991年 | 108篇 |
1990年 | 71篇 |
1989年 | 119篇 |
1988年 | 105篇 |
1987年 | 110篇 |
1986年 | 109篇 |
1985年 | 101篇 |
1984年 | 60篇 |
1983年 | 73篇 |
1982年 | 55篇 |
1981年 | 48篇 |
1980年 | 57篇 |
1979年 | 51篇 |
1978年 | 41篇 |
1977年 | 50篇 |
1976年 | 42篇 |
1975年 | 33篇 |
1974年 | 24篇 |
1971年 | 24篇 |
1925年 | 28篇 |
排序方式: 共有4618条查询结果,搜索用时 15 毫秒
71.
Immunological factors in endometriosis-associated reproductive failure: studies in fertile and infertile women with and without endometriosis 总被引:7,自引:4,他引:7
Martinez-Roman S; Balasch J; Creus M; Fabregues F; Carmona F; Vilella R; Vanrell JA 《Human reproduction (Oxford, England)》1997,12(8):1794-1799
Immunopathophysiological mechanisms in endometriosis-associated
reproductive failure were studied in appropriate populations: infertile and
fertile women with and without endometriosis. The incidence of sera
positive for any of the autoantibodies tested among infertile women with
endometriosis (n = 25) was similar to that observed in the three control
groups [unexplained infertility patients (n = 25) and fertile women with (n
= 10) and without (n = 25) endometriosis]. The mean volume of peritoneal
fluid was significantly elevated in women with endometriosis (both fertile
and infertile) as compared with patients without endometriosis (fertile or
infertile). The concentration of peritoneal fluid leukocytes and the
percentage of cells positive for macrophage markers were significantly
increased and the percentage of T lymphocytes significantly decreased in
infertile women with endometriosis but not in patients with unexplained
infertility and fertile women with endometriosis, as compared with fertile
controls without endometriosis. Macrophages from infertile patients with
endometriosis had higher sperm phagocytosis than did those from infertile
women without endometriosis or fertile subjects with or without
endometriosis. Incidences of serum and peritoneal fluid samples embryotoxic
to the in-vitro development of 2-cell mouse embryos were significantly
higher in infertile patients with endometriosis than in unexplained
infertility patients and fertile women with or without endometriosis. It is
concluded that immunological mechanisms of endometriosis-associated
infertility exist but that these peritoneal immunological factors in
infertile women with endometriosis are related to their subfertility rather
than to the presence of ectopic endometrial implants. This is supported by
the lack of immunological abnormalities observed among fertile women with
endometriosis. These immunological abnormalities are lacking in patients
with unexplained infertility.
相似文献
72.
The ileoanal J pouch: radiographic evaluation 总被引:1,自引:0,他引:1
Endorectal ileoanal pull-through offers an attractive alternative to proctocolectomy and ileostomy for patients with ulcerative colitis, Gardner syndrome, and familial polyposis. To our knowledge, a careful radiographic analysis of the ileum, ileal pouch, and ileoanal anastomosis after ileoanal pull-through has not been reported. Thirty-two patients with ulcerative colitis, Gardner syndrome, and familial polyposis underwent colectomy, mucosal proctectomy, and endorectal ileoanal pull-through of a 15-cm ileal "J" pouch and loop ileostomy. Twenty-five (78%) of 32 of all the pouches radiographically demonstrated spiral folds extending from the middle of the pouch to the pectinate line. Other radiographic features included a mesenteric mass effect, pseudopolyps, and a central lucency that indicated intrapouch sutures. Radiographs provide useful information in the postoperative management of the ileal pull-through. 相似文献
73.
Association of volume with outcome of coronary artery bypass graft surgery. Scheduled vs nonscheduled operations 总被引:14,自引:3,他引:11
J A Showstack K E Rosenfeld D W Garnick H S Luft R W Schaffarzick J Fowles 《JAMA》1987,257(6):785-789
Empirical evidence suggests that mortality rates for coronary artery bypass graft (CABG) surgery are lower in hospitals that perform a higher volume of the procedure. In recent years, the criteria for CABG surgery have been expanded to include patients with a wide variety of co-morbidities. To address the question of whether the volume-outcome relationship continues to exist for this new group of patients, discharge abstracts for 18,986 CABG operations at 77 hospitals in California in 1983 were analyzed using multiple-regression techniques. Higher-volume hospitals had lower in-hospital mortality (adjusted for case mix); this effect was greatest in patients who might be characterized as having "non-scheduled" CABG surgery. Higher-volume hospitals also had shorter average postoperative lengths of stay and fewer patients with extremely long stays. The results of this study suggest that the greatest improvement in average outcomes for CABG surgery would result from the closure of low-volume surgery units. 相似文献
74.
75.
Dave P. Nichols Scott H. Donaldson Carla A. Frederick Steven D. Freedman Daniel Gelfond Lucas R. Hoffman Andrea Kelly Michael R. Narkewicz Jessica E. Pittman Felix Ratjen Scott D. Sagel Margaret Rosenfeld Sarah Jane Schwarzenberg Pradeep K. Singh George M. Solomon Michael S. Stalvey Shannon Kirby Jill M. VanDalfsen Steven M. Rowe 《Journal of cystic fibrosis》2021,20(2):205-212
Highly effective CFTR modulator drug therapy is increasingly available to those with cystic fibrosis. Multiple observational research studies are now being conducted to better understand the impacts of this important therapeutic milestone on long-term outcomes, patient care needs, and future research priorities. PROMISE is a large, multi-disciplinary academic study focused on the broad impacts of starting elexacaftor/tezacaftor/ivacaftor in the US population age 6 years and older. The many areas of investigation and rationale for each are discussed by organ systems, along with recognition of remaining important questions that will not be addressed by this study alone. Knowledge gained through this and multiple complementary studies around the world will help to understand important health outcomes, clinical care priorities, and research needs for a large majority of people treated with these or similarly effective medications targeting the primary cellular impairment in cystic fibrosis. 相似文献
76.
SUMMARY Previous studies have shown that premature infants may be at risk for hypoxemia and bradycardia when placed in standard car seats. However, the relationship of such breathing abnormalities to sleep state have not been studied. The purpose of the present study was to investigate the effect of car seat positioning on respiratory patterns in preterm infants during sleep and to evaluate their relationship to sleep state. Complete polysomnography, including sleep and breathing parameters, was performed on twenty-eight premature infants. Each infant was randomly assigned to the car seat or prone (crib) position for the first recording period. Following the recording of at least two sleep cycles, the position was reversed. The percentage of active and quiet sleep was calculated and breathing parameters were measured. In the car seat, the infants spent significantly more time in active sleep and less time in quiet sleep than in the prone position, of the respiratory parameters, periodic breathing (PB) was significantly higher in the car seat. The presence of at least one abnormal breathing events (bradycardia, desaturation, PB apnoea) was also significantly higher in the car seat. An analysis of variance (ANOVA) of PB revealed significant sleep-state effect (active vs. quiet sleep), but no significant condition or interaction effects, indicating that PB was more frequent in active sleep regardless of the sleeping condition. It is concluded that increased active sleep in the car seat condition, rather than the positioning of the infant in the seat per se, may account for the increase in periodic breathing and possibly other breathing abnormalities reported in car seats. 相似文献
77.
78.
D. L. Rosenfeld J. G. Barone S. Leiman J. D. Quarles M. H. Fleisher 《Pediatric radiology》1995,25(6):466-468
We report an infant with two unique anatomic abnormalities. A flipped kidney in utero is described with the association of a Gartner's duct cyst and a vaginal ectopic ureter with a duplicated collecting system. 相似文献
79.
Tabandeh H Rosenfeld PJ Alexandrakis G Kronish JP Chaudhry NA 《American journal of ophthalmology》1999,128(5):650-652
PURPOSE: To investigate a case of Purtscher-like retinopathy that occurred in association with pancreatic adenocarcinoma. METHOD: Case report. RESULTS: A 63-year-old woman presented with multiple gray patches in the central vision of both eyes. Visual acuity was 20/20 in both eyes. Funduscopy showed large peripapillary yellow-white patches within the superficial retina and small superficial retinal hemorrhages in both eyes. The patient subsequently had abdominal pain. Computed tomography of the abdomen demonstrated a large pancreatic mass with extension into the liver. Histologic examination of a percutaneous needle biopsy specimen showed mucinous pancreatic adenocarcinoma. CONCLUSION: Pancreatic adenocarcinoma should be added to the list of systemic diseases that can be associated with Purtscher-like retinopathy. 相似文献
80.
The linearity of the volume/pressure response during intracranial pressure "reserve" testing.
下载免费PDF全文
![点击此处可从《Journal of neurology, neurosurgery, and psychiatry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
H A Wilkinson S Rosenfeld D Denherder R Bronson 《Journal of neurology, neurosurgery, and psychiatry》1981,44(1):23-28
The intracranial pressure "reserve" test seems to be the most reliable method of determining when the brain''s natural mechanisms for pressure compensation for added intracranial volume have been compromised or exhausted. The test employs a timed sequence of intracranial fluid injections, but as a safety precaution injections are discontinued if intracranial pressure remains elevated more than 10 Torr over baseline. In this case, a linear extrapolation is then calculated to determine the elevation which might have been achieved by a full series of injections. However, this linear extrapolation has been criticised on the expectation that an exponential response should be expected. A series of experimental observations in dogs and baboons and a review of clinical records in humans have been made to determine the observed slope of increase following aliquot injection during performance of the intracranial pressure reserve test. In these species the observed response was actually linear in shape rather than exponential. This held true even for different initial baseline values and with different volumes of "lesion" balloon inflations in experimental animals. A theoretic explanation is proposed. 相似文献