全文获取类型
收费全文 | 185740篇 |
免费 | 17378篇 |
国内免费 | 12351篇 |
专业分类
耳鼻咽喉 | 1622篇 |
儿科学 | 2207篇 |
妇产科学 | 2751篇 |
基础医学 | 20505篇 |
口腔科学 | 3512篇 |
临床医学 | 24123篇 |
内科学 | 27432篇 |
皮肤病学 | 2090篇 |
神经病学 | 9233篇 |
特种医学 | 6604篇 |
外国民族医学 | 95篇 |
外科学 | 19241篇 |
综合类 | 32385篇 |
现状与发展 | 43篇 |
一般理论 | 11篇 |
预防医学 | 13080篇 |
眼科学 | 5070篇 |
药学 | 19504篇 |
215篇 | |
中国医学 | 10691篇 |
肿瘤学 | 15055篇 |
出版年
2024年 | 633篇 |
2023年 | 2809篇 |
2022年 | 7333篇 |
2021年 | 9236篇 |
2020年 | 7030篇 |
2019年 | 6106篇 |
2018年 | 6115篇 |
2017年 | 5918篇 |
2016年 | 5424篇 |
2015年 | 8262篇 |
2014年 | 10312篇 |
2013年 | 9948篇 |
2012年 | 14632篇 |
2011年 | 15752篇 |
2010年 | 10443篇 |
2009年 | 8481篇 |
2008年 | 10663篇 |
2007年 | 10133篇 |
2006年 | 9782篇 |
2005年 | 9082篇 |
2004年 | 6158篇 |
2003年 | 5579篇 |
2002年 | 4585篇 |
2001年 | 4018篇 |
2000年 | 4041篇 |
1999年 | 3992篇 |
1998年 | 2526篇 |
1997年 | 2429篇 |
1996年 | 1779篇 |
1995年 | 1638篇 |
1994年 | 1403篇 |
1993年 | 924篇 |
1992年 | 1317篇 |
1991年 | 1149篇 |
1990年 | 1009篇 |
1989年 | 876篇 |
1988年 | 757篇 |
1987年 | 710篇 |
1986年 | 540篇 |
1985年 | 486篇 |
1984年 | 256篇 |
1983年 | 186篇 |
1982年 | 123篇 |
1981年 | 121篇 |
1980年 | 80篇 |
1979年 | 125篇 |
1978年 | 63篇 |
1976年 | 55篇 |
1975年 | 58篇 |
1974年 | 67篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
An in vivo voltammetry technique was used to monitor the extracellular ascorbate (AA) concentration in the nucleus accumbens and striatum of unanesthetized, freely moving rats. A single injection of ethanol, 1.0 g/kg intraperitoneally (IP), induced a significant increase in extracellular AA concentration in both the nucleus accumbens and striatum. This effect was dose dependent within a dose range from 0.5-2.0 g/kg. 4-Methylpyrazole (50 mg/kg, IP), which inhibits alcoholdehydrogenase, could not prevent the increase in AA concentration, evoked by ethanol. Furthermore, systemic administration of acetaldehyde (20 mg/kg, IP), the main metabolite of ethanol, did not have any effect on the level of AA in the nucleus accumbens or striatum. These results show that ethanol can alter the brain extracellular AA levels and that this effect seems to be attributed to ethanol itself and not to acetaldehyde. Consequently, these results indicate that a role for AA in the action of ethanol in the brain should be considered. 相似文献
72.
73.
A randomized comparative study of levonorgestrel-releasing intrauterine device (LNG-IUD) and NorplantR-2 implants was carried out in 200 women for 36 months. Three thousand one hundred woman-months of use were observed with each device. Only one pregnancy occurred in users of LNG-IUD at the 12th month of use. The change in bleeding pattern was the most frequent reason for discontinuation. The discontinuation rate for irregular bleeding with Norplant-2 was 17.3 and 26.8 at 24 and 36 months, respectively, as compared to 3.3 with LNG-IUD at both 24 and 36 months. The differences were statistically significant. Removal for amenorrhea and pain only occurred in acceptors of LNG-IUD. About 20–40% of women using Norplant-2 had prolonged bleeding through 36 months. The percentage of amenorrhea in LNG-IUD was the highest (29.3%) at the end of two years of use. More than 97% of subjects reported satisfaction with the methods used by themselves.
Resumen Un estudio aleatorizado en el que se comparan los dispositivos intrauterinos que descargan levonorgestrel (LNG-IUD) con los implantes Norplant-2 se realizó en 200 mujeres durante 36 meses. Se observó un período de utilización correspondiente a tres mil cien meses-mujer con cada uno de los dispositivos. Hubo un solo embarazo, en el decimosegundo mes, entre las usuarias de LNG-IUD. La alteración del flujo menstrual fue la razón invocada con mayor frecuencia para el abandono del método. Los porcentajes de abandono por la irregularidad de la menstruación en el caso de los Norplant-2 fue de 17,3 y 26,8 a los 24 y 36 meses, respectivamente, en comparación con 3,3 con los LNG-IUD a los 24 y 36 meses. Estas diferencias son estadísticamente significativas. El retiro por amenorrea y dolores sólo ocurrió entre las mujeres que tenían los LNG-IUD. Los Norplant-2 ocasionaron sangrado prolongado durante los 36 meses estudiados en alrededor del 20 al 40% de las mujeres. El porcentaje de amenorrea con los LNG-IUD llegó al nivel máximo (29,3%) al cabo de dos años de uso. Más del 97% de las mujeres se mostraron satisfechas con los métodos que utilizaban.
Resumé Une étude randomisée comparant les dispositifs intra-utûrins libérant du lévonorgestrel (LNG-IUD) aux implants Norplant-2 a été effectuée sur 200 femmes pendant 36 mois. On a ainsi observé une période d'utilisation correspondant à trois mille cent mois/femme avec chacun des dispositifs. Une seule grossesse s'est produite, au douzième mois, parmi les utilisatrices de LNG-IUD. L'altération du flux menstruel a été la raison le plus souvent invoquée pour l'abandon de la méthode. Les pourcentages d'abandon du fait de l'irrégularité de la menstruation dans le cas des implants se sont élevés à 17,3 et 26,8 après respectivement 24 et 36 mois, alors qu'ils n'atteignaient que 3,3 pour les LNG-IUD, tant à 24 qu'à 36 mois. Ces différences sont statistiquement significatives. Le retrait à la suite d'aménorrhée et de douleurs n'a été constaté que chez des femmes portant les LNG-IUD. Le Norplant-2 a occasionné des saignements prolongés pendant les 36 mois étudiés chez environ 20 à 40% des femmes. Dans le cas des LNG-IUD, le taux d'aménorrhée était le plus élevé (29,3%) au terme de deux années d'utilisation. Plus de 97% des patientes se sont dites satisfaites de la méthode qu'elles appliquaient.相似文献
74.
Early experience with laparoscopic abdominoperineal resection 总被引:4,自引:0,他引:4
Background: Laparoscopic abdominoperineal resection (LAPR) has not been fully evaluated as a technique in the treatment of rectal and
anal cancer or inflammatory bowel disease. The purpose of our study was to evaluate the early experience with laparoscopic
abdominoperineal resection at Washington University Medical Center.
Methods: A prospective analysis was performed on the first 21 patients undergoing the procedure at Washington University Medical Center.
Indications for surgery included rectal cancer (14 patients), anal squamous cell cancer (four patients), inflammatory bowel
disease (two patients), and anal melanoma (one patient).
Results: The procedure was converted to open procedure in four patients (19%). The mean (±SEM) operative time and blood loss for completed
and converted LAPR were 239 ± 11 min and 424 ± 43 ml, respectively. Postoperative hematocrit dropped a mean of 8.3% ± 1.2%
SEM; five patients required blood transfusion (24%). Wound complication occurred in four patients (19%; three perineal, one
trocar site). Bowel function returned after a mean of 3 days, and mean postoperative hospital stay for the completed LAPR
group was 5 days. Mild pain was experienced by 81% of patients (17/21) while 19% (4/21) noted moderate pain, usually of the
perineal wound. The mean duration of patient-controlled analgesia use was 2 days. During the 1–44-month follow-up, six patients
(29%) died from cancer (stage III or IV at operation) and only one patient developed local recurrence in the pelvis (5%).
There were no trocar-site implants of cancer. Furthermore, there was no relationship between prior abdominal operations, the
amount of blood loss, postoperative drop of hematocrit, or blood transfusion requirement and the length of hospitalization
or complication rates.
Conclusion: Laparoscopic abdominoperineal resection is a feasible alternative to the conventional open technique in both cancer and colitis
patients.
Received: 23 April 1996/Accepted: 8 July 1996 相似文献
75.
76.
Meng-Liang Zhou Ji-Xin Shi Chun-Hua Hang Hui-Lin Cheng Xiao-Ping Qi Lei Mao Ke-Fei Chen Hong-Xia Yin 《Journal of cerebral blood flow and metabolism》2007,27(9):1583-1592
Nuclear factor-kappaB (NF-kappaB) plays a key role in inflammation, which is involved in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH). In the present study, we assessed the potential role of NF-kappaB in regulation of cerebral vasospasm. Nuclear factor-kappaB DNA-binding activity was measured in cultured vascular smooth muscle cells (VSMCs) treated with hemolysate and pyrrolidine dithiocarbamate (PDTC, 80 micromol/L), an inhibitor of NF-kappaB. Forty-two rabbits were divided into three groups: control, SAH, and PDTC groups (n=14 for each group). The caliber of the basilar artery was evaluated. Nuclear factor-kappaB DNA-binding activity and the gene expression levels of cytokines and adhesion molecules in the basilar artery were measured. Immunohistochemical study was performed to assess the expression and localization of tumor necrosis factor (TNF)-alpha, intercellular adhesion molecule (ICAM)-1, and myeloperoxidase (MPO). It was observed that NF-kappaB DNA-binding activity was significantly increased by treatment with hemolysate in cultured VSCMs, but this increase was suppressed by pretreatment with PDTC. Severe vasospasm was observed in the SAH group, which was attenuated in the PDTC group. Subarachnoid hemorrhage could induce increases of NF-kappaB DNA-binding activity and the gene expression levels of TNF-alpha, interleukin (IL)-1 beta, ICAM-1, and vascular cell adhesion molecule (VCAM)-1, which were reduced in the PDTC group. Immunohistochemical study demonstrated that the expression levels of TNF-alpha, ICAM-1, and MPO were all increased in the SAH group, but these increases were attenuated in the PDTC group. Our results suggest that NF-kappaB is activated in the arterial wall after SAH, which potentially leads to vasospasm development through induction of inflammatory response. 相似文献
77.
Zhi-gang Wang Yi-dong Huang Ke-luo Cheng Xiao-bi Cai Zheng Wu Jian-dong Zhan 《第一军医大学学报》2004,24(3):345-6, 351
OBJECTIVE: To study how blood supply of the esophageal and gastric stumps influences the anastomotic healing after esophagogastrostomy in rabbits. METHODS: Twenty-seven New Zealand rabbits were randomly divided into 3 groups to receive esophagogastrostomy, followed by different procedures. Except for those in group I, all the rabbits were subjected to procedures of reducing the blood supply either of the esophageal or the gastric stump (group II and group III, respectively), followed by single-layer esophagogastric anastomoses using interrupted 5-0 polypropylene sutures. Ten days after operation, all the rats were killed and the anastomotic sites excised for measurement of the inner diameter, tensile strength, and hydroxyproline concentration. RESULTS: Healing of the esophagograstric anastomosis was obtained in all the rabbits but one with anastomotic leakage in group I and one with perforation of the gastric fundus in group III. The anastomotic inner diameters were similar in all the three groups, whereas the tensile strength and hydroxyproline concentration at the anastomoses decreased in group III in comparison with the other two groups (P<0.05) that had similar measurements (P>0.05). CONCLUSIONS: Extended length of the free esophageal stump does not significantly affect anastomotic healing as decrease of blood supply in the gastric stump. 相似文献
78.
79.
目的探讨胃黏膜内pH值对胆源性胰腺炎病情预后评估及在决定手术冶疗中应用的价值。方法对确诊的146例胆源性胰腺炎患者经鼻插入胃黏膜二氧化碳张力计(TRIP-NGS导管)测定胃黏膜内pH值,每隔12小时测定一次,并进行APACHEⅡ评分,将2组数据与外科治疗进行相关分析。结果①pH值变化反映胆源性胰腺炎病情发展变化,与器官衰竭数呈负相关;②外科干预治疗与内科治疗比较差异有统计学意义(P〈0.05);③pHI〉7.25与pH〈7.25患者开腹手术病死率和细菌培养阳性率比较差异有统计学意义(P〈0.05)。结论pH值对胆源性胰腺炎外科治疗有指导意义。外科处理原则是:①胆道无梗阻,以内科保守治疗为主;②伴胆道梗阻,先行经内镜十二指肠乳头括约肌切开术、经内镜鼻胆管引流术、B超导引引流、腹腔灌洗等,如胆道引流不畅或pH值持续下降,则开腹手术。 相似文献
80.